Many people are confused about science basics when it comes to the inappropriately-named “greenhouse” effect.
This can be easily demonstrated in many blogs around the internet where commenters, and even blog owners, embrace multiple theories that contradict each other but are somehow against the “greenhouse” effect.
Recently a new paper: Scrutinizing the atmospheric greenhouse effect and its climatic impact by Gerhard Kramm & Ralph Dlugi was published in the journal Natural Science.
Because of their favorable comments about Gerlich & Tscheuschner and the fact that they are sort of against something called the “greenhouse” effect I thought it might be useful for many readers to find out what was actually in the paper and what Kramm & Dlugi actually do believe about the “greenhouse” effect.
Much of the comments on blogs about the “greenhouse” effect are centered around the idea that this effect cannot be true because it would somehow violate the second law of thermodynamics. If there was a scientific idea in Gerlich & Tscheuschner, this was probably the main one. Or at least the most celebrated.
So it might surprise readers who haven’t opened up this paper that the authors are thoroughly 100% with mainstream climate science (and heat transfer basics) on this topic.
It didn’t surprise me because before reading this paper I read another paper by Kramm - A case study on wintertime inversions in Interior Alaska with WRF, Mölders & Kramm, Atmospheric Research (2010).
This 2010 paper is very interesting and evaluates models vs observations of the temperature inversions that take place in polar climates (where the temperature at the ground in wintertime is cooler than the atmosphere above). Nothing revolutionary (as with 99.99% of papers) and so of course the model used includes a radiation scheme from CAM3 (=Community Atmospheric Model) that is well used in standard climate science modeling.
Here is an important equation from Kramm & Dlugi’s recent paper for the energy balance at the earth’s surface.
Lots of blogs “against the greenhouse effect” don’t believe this equation:
Figure 1
The highlighted term is the downward radiation from the atmosphere multiplied by the absorptivity of the earth’s surface (its ability to absorb the radiation). This downward radiation (DLR) has also become known as “back radiation”.
In simple terms, the energy balance of Kramm & Dlugi adds up the absorbed portions of the solar radiation and atmospheric longwave radiation and equates them to the emitted longwave radiation plus the latent and sensible heat.
So the temperature of the surface is determined by solar radiation and “back radiation” and both are treated equally. It is also determined of course by the latent and sensible heat flux. (And see note 1).
As so many people on blogs around the internet believe this idea violates the second law of thermodynamics I thought it would be helpful to these readers to let them know to put Kramm & Dlugi 2011 on their “wrong about the 2nd law” list.
Of course, many people “against the greenhouse thing” also – or alternatively – believe that “back radiation” is negligible. Yet Kramm & Dlugi reproduce the standard diagram from Trenberth, Fasullo & Kiehl (2009) and don’t make any claim about “back radiation” being different in value from this paper.
“Back radiation” is real, measurable and affects the temperature of the surface – clearly Kramm & Dlugi are AGW wolves in sheeps’ clothing!
I look forward to the forthcoming rebuttal by Gerlich & Tscheuschner.
In the followup article, Kramm & Dlugi On Dodging the “Greenhouse” Bullet, I will attempt to point out the actual items of consequence from their paper.
Further reading - Understanding Atmospheric Radiation and the “Greenhouse” Effect – Part One and New Theory Proves AGW Wrong!
Note 1 – The surface energy balance isn’t what ultimately determines the surface temperature. The actual inappropriately-named “greenhouse” effect is determined by:
- the effective emission height to space of outgoing longwave radiation which is determined by the opacity of the atmosphere (for example, due to increases in CO2 or water vapor)
- the temperature difference between the surface and the effective emission height which is determined by the lapse rate
SoD.
Perhaps I’m mistaken but you seem to have asked your readers to examine this new paper but without providing a link.
So here it is (again?).
http://www.scirp.org/journal/PaperInformation.aspx?paperID=9233
Thanks, I have updated the article.
SoD
It would be helpful if the term “backradiation” was dropped.
Its unfortunate that the term is used even in the most up to date K&T energy budget diagram.
As you have confirmed in the past, the 333W/m2 flow contains energy contributions that have no origin in radiation from the Earth surface.
You indicated that the term downwelling long wavelength radiation is a more accurate description.
G&T have always said that colder objects radiate to warmer surfaces.
The idea that G&T thought otherwise stems from the deeply flawed Halpern et al paper.
What G&T dispute is the magnitude of such radiation and calling iall 333W/m2 backradiation gives them proof that their concerns are justified.
Bryan:
I got this idea about G&T from reading the G&T paper.
Can you identify where in the paper On Falsification Of The Atmospheric CO2 Greenhouse Effects they clarify:
a) that colder objects radiate to warmer surfaces
b) their views on the magnitude of this downward longwave radiation
SoD
There are several diagrams of objects radiating to one another.
For example Pages 17,20.
Radiation from the colder Earth in all directions including to the warmer Sun.
And different ways to calculate this radiation are all over the near 100pages
Comment on page 41 that atmospheric radiation is “only directed downward is rather obscure.”
Point 9 of page 91 and so on.
That someone reading G&T can come to the firm conclusion that they said that colder objects cannot radiate to warmer surfaces is very hard for me to understand.
Certainly nowhere in their paper have they said this.
Two way radiative transfer is standard physics which G&T certainly know.
One reason perhaps for non physicists to get confused by their writing is their correct insistence that heat cannot move spontaneously from a colder to a hotter surface.
If someone is confused about the difference between heat and radiation they can perhaps be left with the wrong impression.
Their paper was written for a Physics Journal where this is a point that should not have to be explained.
Joel Shore one of the authors now admits that they got their terminology mixed up on this very point.
G&T say very little about backradiation in their paper.
In their reply paper G&T comment some more on backradiation saying that they doubted the magnitude claimed for it.
Until 1879, Stefan was only the term of “thermal radiation” from warm to cool. When they had penetrated deeper into the laws of radiation, it became clear that the simple term “heat radiation” specifically the “net heat radiation” is. For the two components had to be invented new terms, which is a “back radiation” (from cool to warm), the other part (from warm to cool) has no generally accepted names.
Jochen Ebel,
Some people are terribly concerned that if the term “back radiation” is used the reality of the climate system might be lost.
The reality being that some of the radiation emitted by the atmosphere has been absorbed directly from the sun, whereas the balance has been absorbed from the earth’s surface (after previously being absorbed from the sun or from the atmosphere).
And so, if we call it “back radiation” then it might imply something that isn’t quite accurate to some people who don’t understand the subject and that would be upsetting for everyone.
Or something.
That is, it might imply the atmosphere is only radiating energy directly received from the earth’s surface, hence “back..”, rather than some from the sun and some from the atmosphere. And this is all part of the master plan of climate scientists to mislead people who will never read a textbook on atmospheric physics.
Or something.
I’m not sure whether I prefer the term downward longwave radiation (DLR) because it conveys a little more or because that was the term I first read in textbooks and papers.
They might be “terribly concerned”, but the concern still seems misplaced to me. After all: the other way to address it is to bring up a point that needs to be mentioned anyway: that the atmosphere absorbs very little radiated energy from the sun, since the incoming radiation is peaked in the yellow (didn’t you give a figure of less than 1% longwave?). It is only because that incoming energy is re-radiated from the earth’s surface at a much longer wavelength that we get GHG absorption in the atmosphere at all.
I am sure it is not news to you that people often miss this point: for energy coming in from the sun, the atmosphere is transparent. For energy going out to space, it is FAR from transparent. That is what makes the “greenhouse effect” possible in the first place.
Matt J says
” that the atmosphere absorbs very little radiated energy from the sun, since the incoming radiation is peaked in the yellow ”
I think you should look at the KT2008 energy budget diagram.
For every two Joules absorbed by surface one Joule is absorbed by atmosphere.
After albedo reflection the atmosphere absorbs a fraction 78/161 = 48% of the Earth surface absorption
Bryan, I think for your fraction you mean 78/239 = 33%.
SoD says
“Bryan, I think for your fraction you mean 78/239 = 33%.”
No I stand by my calculation based on KT2008
Amount absorbed by atmosphere/amount absorbed by earth surface
= 78/161 = 48%
Or to put it in English for every two Joules absorbed by Earth surface one Joule is absorbed by the atmosphere.
SoD
You asked:
“Can you identify where in the paper On Falsification Of The Atmospheric CO2 Greenhouse Effects they clarify:
a) that colder objects radiate to warmer surfaces
b) their views on the magnitude of this downward longwave radiation”
Let me quote the G & T paper (page 339):
The renowned German climatologist Rahmstorf has claimed that the greenhouse effect does not contradict the second law of thermodynamics:
“Some ‘sceptics’ state that the greenhouse effect cannot work since (according
to the second law of thermodynamics) no radiative energy can be
transferred from a colder body (the atmosphere) to a warmer one (the surface). However, the second law is not violated by the greenhouse effect,
of course, since, during the radiative exchange, in both directions the net
energy flows from the warmth to the cold.”
Then, G & T argued:
“Rahmstorf’s reference to the second law of thermodynamics is plainly wrong. The second law is a statement about heat, not about energy. Furthermore, the author introduces an obscure notion of “net energy flow.” The relevant quantity is the “net heat flow,” which, of course, is the sum of the upward and the downward heat flow within a fixed system, here the atmospheric system. It is inadmissible to apply the second law for the upward and downward heat separately redefining the thermodynamic system on the fly.”
All results of global energy budgets that can be found in the respective literature document that G & T are right. The so-called net radiation in the infrared range (IR) is directed upward, on global average, i.e., considerably more IR radiation is emitted by the Earth’s surface than by the atmosphere in downward.direction. Note that IR radiation is isotropically emitted.
In the 2nd law of thermodynamics the term
- 1/T^2 R grad(T) >= 0
occurs in the entropy source function. Here, R is the radiation flux, T is the abs. temperature, and grad means the gradient usually expressed by the del operator. The term is greater than or equal to zero. IR radiation must fulfill this condition. In case of solar radiation it is not so simple because one can focus solar radiation with an ice lens to burn, for instance, wooden material.
In subsection 3.5 of the G & T paper the basics of the transfer of IR radiation is considered. These basics are correct. If the source function in the radiative transfer equation is considered and expressed by the Planck function as justified by the papers of Einstein (1917) and Milne (1928) then the emission of IR radiation will depend on the temperature of the radiating gases like water vapor, carbon dioxide, ozone, and nitrous oxide.
In Fall 2007 I got a copy of the arXiv-version of the G & T paper. Prof. Dr. Akasofu asked me to express my opinion on this paper. I read it during the next couple of months and eventually started to defend it especially on dot.earth of the NYT. I know this paper well and I have the impression that most blogger who criticized it have never read this paper or are not well familiar with textbook knowledge.
If, as your post clearly implies, you think “1/T^2 R grad(T) >= 0″ is “a term of the 2nd law of thermodynamics”, then you are the one who needs to review textbook thermodynamics.
If that is not what you really believe, then you really need to learn how to write. For that is what your post strictly implies.
As SoD has already shown, the G&T paper is full of severe methodological errors that in turn imply that the authors either do not know thermodynamics (especially of radiated energy) or are simply being dishonest.
SoD,
I strongly disagree that the greenhouse effect is inappropriately named. The confusion about this apparently results from believing that Wood in 1909 was correct and that the IR transparency of glazing of an horticultural greenhouse makes no difference to the internal temperature. This is simply wrong. As someone else put it, it might be approximately true for a greenhouse with very thin walls in a very windy climate. It is not true for a well insulated greenhouse.
Abbot doubted the validity of Wood’s results in 1909 and recent attempts to do similar experiments by Vaughan Pratt, Nasif Nahle and myself all show that a box painted black on the inside, covered with an LW (> 4μm wavelength) IR transparent window and oriented so that the bottom surface is normal to incoming solar radiation has a lower internal temperature than a similar box with an IR opaque window such as 2+mm thick glass, acrylic or polycarbonate. Note that Nahle’s experiment appears to give the same result as Wood, but his LW transparent windowed box has more insulation, ~1″ fiberglass, than his LW opaque windowed boxes which were only covered with Al foil. He shows later that the fiberglass insulation increases the box temperature by 10 C compared to a box covered only with Al foil.
The IR transparent windowed box also cools faster and reaches a lower internal temperature than a similar box with a glass window when exposed to a clear, cold night sky. The size of the effect is dependent on how well the boxes are insulated. A planetary atmosphere is effectively perfectly insulated from non-radiative heat loss. The basic physics are otherwise identical. Lowering emissivity, whether by using LW IR opaque windows in a greenhouse or adding IR absorbing gases to the atmosphere has exactly the same result, higher temperature.
The absorptivity of air is negligible in the Wood test. For heat transport (including the radiant heat transfer), a temperature difference is required (second law of thermodynamics). Since the convection in the interior is not stopped, the proportion of radiative transfer for the thermal equilibrium is negligible. Since the radiation transport is negligible, the fraction of absorption in air are even more. The lack of the Wood experiment shows itself in the use of only a thermometer. How will so the temperature difference measured in the test chamber?
But nevertheless, the term for both greenhouse is fit . The temperature increase inside the Wood experiment follows from the thermal resistance of the envelope, in the case of the atmosphere from the resistance of the radiant heat transfer in the air.
Not true. The absorptivity of air is not relevant. It’s the absorptivity of the window that’s important. Polyethylene film is nearly transparent for radiation with wavelengths greater than 4 μm while glass is nearly opaque. What you seem to be neglecting is that the glass window will be at a lower temperature than the radiating surfaces of the box. It must then radiate less and the temperature inside must go up. Radiative transfer is only negligible if the temperature difference between the inside of the box and the outside is small, i.e. really bad insulation.
But a simple wall has significant thermal insulating properties because of the stagnant film of air on each side. So in the absence of wind, the thermal resistivity of an uninsulated cardboard box is about 1 in imperial units ( R value ) or 0.18 K/(W/m²) in SI units. Even that is sufficient to produce a temperature difference inside the box of nearly 2 C between a box covered with polyethylene film window and a box covered with a glass window. With really good insulation (>6 inches of fiberglass batting), the internal temperature is about 80 C higher than ambient and the temperature difference between a box with an LW IR transparent window and a box with a glass window is >10C. ( http://i165.photobucket.com/albums/u43/gplracerx/heavilyinsulatedplasticboxes.jpg , channel 1 is ambient air, channel 2 is the polyethylene film windowed box and channel 3 is the glass windowed box ). That doesn’t look negligible to me. With multiple layers of LW IR opaque windows, the temperature goes up even more ( http://i165.photobucket.com/albums/u43/gplracerx/multilayerbox1.jpg )
This experiment is very similar to the toy model of a single slab gray atmosphere. The toy model is normally used in the limit of perfect thermal insulation, but it can be expanded to include finite heat loss to the surroundings and to the slab by conduction/convection and the numbers work out quite well.
DeWitt Payne
It looks like you have spent a lot of time on this project.
It would be a pity if you did not do a full write up with apparatus, diagrams, method, result and conclusion.
Until you do that you cannot expect us to “take your word for it”.
Your result contradicts Wood Nasif Nahle and this extensive project spread over a number of years .
It gives massive support for the conclusions of the famous Woods experiment.
Basically the project was to find if it made any sense to add Infra Red absorbers to polyethylene plastic for use in agricultural plastic greenhouses.
Polyethylene is IR transparent like the Rocksalt used in Woods Experiment.
The addition of IR absorbers to the plastic made it equivalent to “glass”
The results of the study show that( Page2 )
…”IR blocking films may occasionally raise night temperatures” (by less than 1.5C) “the trend does not seem to be consistent over time”
http://www.hort.cornell.edu/hightunnel/about/research/general/penn_state_plastic_study.pdf
Bryan,
I’ve already told you why the Penn State study is irrelevant. But I’ll do it again. The Penn State experiment was mainly looking at crop yields. Temperature is only one variable for crop yield. They were using high tunnel greenhouses, which means open ended, approximately hemispherical tunnels over moist ground. That is in no way comparable to Wood who used boxes with insulated walls.
It is no more and no less ‘my word’ than Nahle, Pratt, Roy Spencer or even Wood’s results. I’ve posted actual experimental data. I’ve posted pictures of the apparatus. In fact, you have far more details of all of the recent experiments than you do of Wood. I’ve even pointed specifically to the details of Nahle’s experiment that confirm they support the conclusion that Wood was wrong. Did you ever look at that? You could do the experiment yourself. All you need is some glue, a utility knife, a ruler, some half inch thick foam art board, black paint, aluminum foil, some food cling wrap, a piece of glass or plastic and a couple of thermometers. But you won’t because you might then have to admit that you were wrong about something.
Wood’s papers were contradicted at the time:
From Vaughan Pratt
For anyone else reading this, I think it would make a good Science Fair project.
DeWitt Payne says
“The Penn State experiment was mainly looking at crop yields. Temperature is only one variable for crop yield.”
Yes but Wood Nasif Nahle and yourself are also measuring temperatures so it is highly relevant.
I am only commenting on the measured temperatures.
Its beginning to sound like we will never see a proper write up of your experiments and that would be a pity.
If I had a full write up I would like to repeat your experiment.
Saying that one bit is like Wood and another bit like Nasif Nahle or Vaughan Pratt is just not good enough.
I’m thinking that the real test would be two identical boxes at night except that one has 6mm IR absorbing polyethylene and the other 6mm clear polyethylene
Bryan,
I’m nowhere near done and we’ve just had Christmas and New Years. Patience.
6mm is way too thick. Even unmodified polyethylene would be IR opaque at that thickness. 0.5 mil polyethylene only transmits about 90% of the incident thermal IR. You can tell because the apparent temperature of an object measured with an IR thermometer is lower when viewed through polyethylene film. Window glass is only 2.4 mm thick.
But I can do something very similar. I have some 1 mil ( 25.4 μm ) thick polyester film that absorbs much more strongly in the IR than polyethylene. That’s also very close to the thickness of the polyethylene film I’m using. I’ve done a quick and dirty experiment with polyethylene film and glass windowed boxes and the film covered box cools much faster to lower temperature than the glass covered box. For a single layer in the absence of wind, the thermal resistivity of the barrier, unless it’s something like aerogel, doesn’t make much difference. They’ve gutted the article on R value at Wikipedia or I’d reference it.
DeWitt Payne
I’m glad you are going to do a full write up.
It would seem a pity after all your efforts and it could be easily dismissed by critics.
The rigidity of 6mm polyethylene is a bonus and the two boxes being identical except for IR absorbing material eliminates unnecessary variables.
I note what you say about
“6mm is way too thick. Even unmodified polyethylene would be IR opaque at that thickness.”
I will look into this, but since all that is required is a differential between the two polyethylene types, it might still be possible.
Gerhard Kramm
On another thread SoD and I were exchanging views on your excellent new paper.
One thing about the equation2.17 that I would seek clarification on is the definition of Rs.
Do you mean the total incoming solar radiation?
To mention diffusive radiation here perhaps creates uncertainty coupled with the fact that Rs is then perhaps due to be corrected for reflection by albedo of around 0.3.
Gerhard Kramm,
Thanks for stopping by.
When I read the G&T paper I could see three choices for their obscurantist approach to explanation:
1) They didn’t understand atmospheric radiation despite their wonderful ability to perform double integrals and their ability to cite (but not solve) the radiative transfer equations – i.e., they didn’t believe the atmosphere radiated to the surface (or it couldn’t be calculated because it was too complicated – who would know after their amazing comments about all the things they claim are impossible to calculate even though they actually are in practice?)
2) They believed the atmosphere radiated to the surface but the energy disappeared, or was absorbed without affecting the surface temperature.
3) They actually believed that the presence of a radiatively-active atmosphere affected the surface temperature of the earth but were having a huge joke by pretending they didn’t.
Item 2 would mean they didn’t believe the first law of thermodynamics and I thought that was by far the least likely.
Item 3 is actually what I really thought but who would take the time to write such a paper knowing how many hundreds of thousands – or millions it would confuse? Not their problem if the readers haven’t studied physics? No, it seemed more charitable to assume good motives yet confused understanding.
So I was left with item 1.
Whether or not they intended it they have definitely assisted in convincing a large part of the internet world who don’t understand radiative heat transfer that:
i) cool objects don’t radiate towards hot objects, and/or
ii) hot objects can’t absorb the radiation from cool objects,
iii) if i) and ii) were possibly correct it couldn’t affect the temperature of the hotter object.
But nowhere in their paper have they clarified that cool objects radiate towards hotter objects, nor have they clarified that this energy is absorbed, nor have they clarified that the absorbed energy changes the internal energy of the hotter object.
Of course, these points are implied in the equations of radiative heat transfer – which is why I have to write articles like The Three Body Problem and especially Amazing Things we Find in Textbooks – The Real Second Law of Thermodynamics – and just check out the responses by the most enthusiastic advocate of G&T on that article and the many previous ones. See what great work they have done.
No doubt they will say “not our problem“. Up to them if they want to have a laugh. I appreciate a good joke, but I’d be ashamed if I had written a paper like that.
SoD
The dry adiabatic lapse rate formula is derived with no reference to radiation.
Hydrostatic equilibrium is the condition for the derivation of the formula.
In fact it does not even assume convection is taking place.
The still air atmosphere is called the neutral atmosphere.
It is often quite stable particularly at night.
So how then do we have a temperature profile given by?
DALR = -9.8K/km
It would appear then that a significant means of heat transfer is by diffusion for the neutral atmosphere.
So where is the radiation in the neutral atmosphere?
We need to remember the fact that the heat capacity of a gas(Cp) contains a lot of thermodynamics.
Many treat it as a constant and leave it at that but that is an gross oversimplification.
For instance the formula for the dry adiabatic lapse rate is given as
DALR = -g/Cp
Yet a moments consideration will tell you that the air contains CO2 with all its radiative properties.
These radiative properties are included in the bulk quantity Cp
If we examine how Cp changes with temperature for two different gases the point will become clearer.
A range of 250K to 350K will cover most atmospheric situations.
For Nitrogen (N2) the values vary by 0.2% i.e. almost constant
For CO2 the values vary by 13.1%
Why does CO2 change so much?
Because other degrees of freedom besides translational become possible for CO2 as the temperature changes.
These extra degrees of freedom correspond to the 4um and 15um thermal em wavelengths
Point being that if accurate values of Cp are used as the temperature changes then all the radiative effect are included!
IPCC advocates on the other hand want to deal separately with radiation forgetting that it has already been included in Cp.
This leads to double counting and the absurd greenhouse effect.
For air with a trace of CO2 the radiative effects are very small so there is a linear decrease in temperature with increasing altitude.
The DALR would be almost constant at -9.8K/km.
If the Earths atmosphere was 100% composed of CO2 then at;
300K …………..DALR = -11.6K/km
250K …………..DALR = -12.4K/km
So no longer a linear relationship as Cp is no longer constant but varies significantly with temperature.
For the adiabatic lapse rate:
This only occurs if the temperature gradient would be greater than the lapse rate without vertical circulation. This “bigger” is the drive for the vertical circulation. This vertical circulation reduced the temperature gradient due to convective heat transport to the adiabatic value. In fact, the observed lapse rate due to heat transfer and radiation differs somewhat from the ideal lapse rate, but this difference is very small because of the high mobility of the air.
Sorry so late with this, but radiation is implicit in the value chosen for surface temperature in the adiabatic lapse rate calculation.
The radiative properties (or radiation) is included (or implicit) in the bulk quantity Cp for an IR active gas at a particular temperature
Bryan,
You’ve missed the point again. Yes Cp does depend on T. But Tsurface is determined by the magnitude of the absorbed incoming radiative flux at the top of the atmosphere and the environmental lapse rate. If the Earth’s orbit were at a radius of 1.1 AU, it would be colder. If it were at 0.9 AU, it would be warmer.
Energy of electromagnetic radiation is not “implicit in Cp of atmospheric gases”. Electromagnetic radiation in equilibrium with its local environment has its own heat capacity but it’s very small (about 0.00000007 J/m3/K at the temperature of the lower atmosphere). Furthermore that energy is not significantly influenced by the properties of the gas except that interaction is needed to maintain even approximately the local thermodynamic equilibrium.
The radiative effects have thus nothing to do with Cp, they are important for the transfer of heat from one point in the atmosphere to another, for heat transfer between the surface and the atmosphere, and most importantly from the atmosphere to the space.
Cp of CO2 does vary with temperature, because the vibrational modes are discrete and get more important with increasing temperature, but this again has nothing to do with the role these vibrational modes have in interaction with radiation. They would influence Cp equally even if they would not interact with IR at all. Their influence on Cp is totally due to excitation and de-excitation of these modes through molecular collisions, radiation has no significant role in that.
De Witt Payne and Eli Rabett
Who says a volume of gas can only be heated by radiation?
Only radiation junkies I suppose!
Pekka Pirilä
“Their influence on Cp is totally due to excitation and de-excitation of these modes through molecular collisions, radiation has no significant role in that.”
Of course the vibrational modes can be excited/de-excited by collision but also by absorption/emission of (for instance) 15um radiation.
You appear to be saying that for CO2, radiation has no role in that!
Bryan,
The vibrational modes are essential for radiative processes, but the radiative processes have very little influence on the vibrational modes. Something like 99.99% of all excitations and de-excitations are due to collisions in troposphere. In addition radiation is usually not far from balance and thus even the minuscule role that it has in all transitions influences the balance even less.
Radiative transfers have a much more important role near the top of stratosphere and beyond, because collisions are so much more rare in the rarefied gas of those altitudes,
Pekka Pirilä
I don’t disagree with much that you say however it is not the full story.
Take a mole of CO2 (to make sure of macro events) and place it in an IR transparent enclosure at STP, surrounded by a vacuum in space at approximately zero Kelvin.
Then measure the emitted IR as the temperature drops.
I’m pretty sure that the IR readings would drop in a predictable and repeatable way.
So the IR radiational activity in an IR active gas at a particular temperature is implicit and inextricably linked to the bulk thermodynamic quantity Cp of the gas.
Bryan,
The emission from a small volume of gas that contains no other emitters of IR than CO2 is proportional to the CO2 concentration and the strength of emission depends on the temperature according to Planck’s formula. When the gas cools its emission decreases.
Nothing in the above is directly related to Cp.
I don’t claim that there isn’t any connection, but it’s rather roundabout. The connection comes from the fact that Planck’s formula contains a factor that’s proportional to the number of molecules in the excited state. That same number influences also Cp as the vibrational modes do increase significantly Cp only when their occupation level is not very low. The contribution of a vibrational mode to specific heat is proportional to the dependence of the occupation level on temperature, and that dependence is bound to be small as long as the whole level remains small.
Pekka,
Oh? The rate of temperature decrease depends on the heat capacity of the gas and the rate of energy loss. That would seem to be directly related to Cp. OTOH, Bryan’s example is irrelevant to the real atmosphere where, on average, there is little heating and cooling and the contribution from CO2 to the total heat capacity of a volume of the atmosphere is miniscule.
Bryan,
So there is some other significant source of energy to the Earth system than solar radiation? That would be news. You did read that I specified the absorbed solar radiation at the TOA, didn’t you? The only other source of energy that I know of would be geothermal from radioactive decay in the Earth’s core. That’s a very tiny fraction of the total.
Pekka,
I’ve discussed this at length with Bryan before. It didn’t seem to help. The symmetric stretch mode of CO2, for example, is not radiatively active because it doesn’t change the dipole moment. Of course at 300 K, it doesn’t contribute much to the heat capacity of CO2 either.
DeWitt,
I tried to state clearly that the rate of temperature decrease is affected by the power of energy loss and that this power is influenced by concentrations and (molecular) emissivities as well as the temperature.
The other factor, heat capacity or Cp, is basically a property of the substance (molecule in case of gas) and also influenced by the temperature.
The rate of temperature decrease is, of course, equal to net energy loss divided by the heat capacity.
—–
One more comment on why I referred to a small volume in one of the above messages. That was to restrict the comment to situations where absorption is always weak and no saturation of absorption occurs. Large enough isothermal volumes of gas are always black bodies but “large enough” is really huge for radiatively inactive gases like N2, and huge means here something much, much larger than the thickness of the Earth atmosphere. With the constitution of the Earth atmosphere the full thickness of the atmosphere would be almost enough, but the Earth atmosphere is not isothermal. At the center of the 15 µm peak a layer of 100 m is almost fully opaque and isothermal enough, but that applies only to that particular wavelength.
Pekka,
At the peak absorption for CO2 at 667.5 cm-1, 1 m is sufficient for transmittance nearly equal to zero at a volumetric mixing ratio of 0.00039 at 1013.25 mbar and a temperature of 296 K. For 100m, there is still observable structure in the band but the transmittance is less than 0.2 from ~650-680 cm-1 and zero from 666.5-670 cm-1 ( http://www.spectralcalc.com , you can do this sort of calculation for free.) For a 1 cm path length, the transmittance at the peak is about 0.96.
Indeed. Collision Induced Absorption is really weak for diatomic molecules. It does appear to be significant for water molecules. Although, as I remember, the attribution of the water vapor continuum absorption to CIA is still controversial.
SoD says
” i.e., they didn’t believe the atmosphere radiated to the surface”
Can you find even one passage is the G&T paper to support this absurd accusation?
If you cant criticize the actual paper don’t invent opinions for G&T ,
G&T’s publisher should be even more ashamed. A paper full of so much misinformation should never have been published in a “peer reviewed” journal. It does great damage to the credibilities not ust of the publisher, but of the reviewers, and even of the peer review process itself.
Matt J.
please write a comment on this paper of Gerlich and Tscheuschner (2009) if you are convinced that it is so bad. However, do me a favor and present a much better comment than that of Halpern et al. (2010). This comment is, indeed, so bad that iI will never understand why it was published. By the way, the 2009 version of Halpern et al. was rejected by the IJMPB. Eventually it was accepted, but the number of mistakes was nearly the same. The question is: Why?
Best regards
Gerhard
Maybe because the German editor was in bed with G&T and it took an appeal to the editorial board to go around the lad?
My take on the comment publication is rather Machiavellian.
Several of the Halpern et al crew had made disparaging attacks on IJMPB journal itself.
Impact factor and so on.
So what better than to publish the ‘comment ‘ paper (mistakes included) to let the World know of the quality of the critics.
Well, Eli hears that the original paper was submitted to Wolfgang whatever his name who Kramm canned it, and it took an appeal to the entire editorial board to get the thing published. Just saying. (PS G&Ts “reply” was even worse than the original) so no, you would be wrong.
SoD
G & T presented the formal solution of the radiative transfer equation for monochromatic intensity (see their Eq. (62)). This solution is independent of the form of the source function. To my best knowledge, this solution was first presented by Chandrasekhar.
This source function usually contains both emission and multiple scattering, i.e., scattering of radiation into the path of the pencil of radiation. In case of IR radiation the latter plays only a role if small ice crystals are considered. Thus, in case of IR radiation the source function is substituted by the Planck function (strictly spoken by the Kirchhoff-Planck function). Even though single scattering and multiple scattering are negligible in such a case, the formal solution can only be finally solved numerically because the distribution of temperature and various traces species have to be considered.
Furthermore, the formal solution has to be formulated in such a sense that the boundary conditions at the bottom and the top of the atmosphere can be addressed. In case of the approximation for the so-called plane-parallel atmosphere it results in two solutions for the upward and the downward directed intensities (e.g., Liou, 2002).
Moreover, the integrations over all frequencies (alternatively wavelengths) have to be performed to obtain the total intensities,and in a further step, the radiative fluxes, There are several ways to perform these integrations because gases emit and absorb only in bands or even in lines (see Petty Grant’s comment or his book on radiation), where also line broadening has to be considered. Unfortunately, there are also overlapping effects.
Nevertheless, to predict the temperature change with respect to time, not the magnitude of the radiative flux is important, but the divergence of the radiative flux. A lot of bloggers do not understand this.
Best regards
Gerhard
The radiation transport equation is only superficially a calculation of the radiation at a given temperature. If only radiant heat transfer, the radiative transfer equation yields a reversed to a temperature profile.
The surface boundary condition is incorrect. The two boundary conditions are:
- Infrared radiation from space = 0
- Radiation into space = absorbed solar radiation.
The temperature at the surface then occurs so that the two conditions are met. If the adiabatic limit would be exceeded at a hypothetical quiescent atmosphere, then outcome convection. Therefore is necessary, inclusion of the convection into the solution of the temperature profile.
In steady state, the divergence of the radiation flux is zero. But the temperature profile is stationary so, that the divergence of radiation flux at this temperature profile is zero. The reversal of cause and effect is just to mislead.
Jochen Ebel:
The first boundary condition is correct and allows calculation of the downward radiation through the atmosphere.
But the second boundary condition you cite is not correct.
Across the long term globally radiation into space = absorbed solar radiation, assuming no heating or cooling of the climate.
But for a given location and time this is not even close to accurate and so the boundary condition for upward radiation is the emission of thermal radiation from the surface.
If the temperature profile of the atmosphere is accurately known this provides the required information to calculate the solution.
If the temperature profile of the atmosphere is not known then a convective model provides a useful estimate.
I don’t understand what you are saying here. What reversal of cause and effect?
I can’t see anything wrong with Gerhard Kramm’s statement above.
Professor Kramm: Thanks for taking the time to comment at this site. Your paper (and the G&T papers which preceded it) tell us that many commonplace descriptions of the greenhouse effect are flawed or inaccurate, at least partially because averaging over the surface of a whole planet or moon introduces large errors. Your information about the temperature of the moon’s surface was startling. It’s obvious that this retired PdD chemist reads in many places is over-simplified or wrong.
Your paper tells us things that are wrong, but doesn’t tell us what is right. Calculus was flawed until a proper definition for limits was created centuries after Newton. There [apparently] are still controversies over how to interpret the meaning of wave functions in quantum mechanics. Both calculus and quantum mechanics give/gave useful results despite these problems. Is the convention explanation for the greenhouse effect “useful” despite the problems you describe?
I’d like to propose a thought experiment that might clarify whether the greenhouse effect is useful a useful concept. Suppose GHG molecules could sense the direction of the earth’s gravitation field and always emitted photons “away” from the earth. (Same emission rate, same anisotropy of emission except for changing sign of the vertical component of those that would normally head downward, maintain the same probability and anisotropy of absorption, leave the number and location of water molecule unchanged.) This would eliminate downward long wavelength radiation from the atmosphere to the surface of the earth – the essence of the greenhouse effect* – but minimally change little else. 1) What would happen to the temperature of the surface of the earth? 2) If there were a change in surface temperature, does the magnitude of this change depend on the total number of GHG molecules in the atmosphere?
* I think the essence of the greenhouse effect is that GHG molecules obstruct (by absorption, emission and scattering) the NET outward flux of radiation from the earth (more than they obstruct the downward flux from the sun).
SOD wrote about G&T: “But nowhere in their paper have they clarified that cool objects radiate towards hotter objects, nor have they clarified that this energy is absorbed, nor have they clarified that the absorbed energy changes the internal energy of the hotter object.”
The internal energy [of the surface of the earth] won’t change if an increase in convection removes it. In 1D models of radiative-convective equilibrium (not necessarily the real world), convection has reduced the steepness of the lapse rate to the maximum compatible with stability. Under these equilibrium circumstances, DLR won’t raise surface temperatures above the temperature determined by the lapse rate, the altitude of the critical emission level and incoming solar radiation reaching the surface and lower atmosphere. The greenhouse effect would only operate where convection is not needed to prevent development of an unstable lapse rate.
Unfortunately, I have can’t to express this concept in the context of the 2LoT.
I clarified this a little more in point iii) of my comment of January 5, 2012 at 8:50 am.
Extract: “..1J absorbed from a colder body has exactly the same effect on internal energy as 1J absorbed from a hotter body – there is absolutely no distinction. Radiation absorbed from cool bodies by hotter bodies slows down the rate of heat loss from the hotter body because more radiation is transferred in the other direction.“
Your statement – “Lowering emissivity, whether by using LW IR opaque windows in a greenhouse or adding IR absorbing gases to the atmosphere has exactly the same result, higher temperature.” – holds only in case of constant gas pressure wiithin the volume considered.
However,this condition does not apply for the Earth´s atmosphere..Therefore no “back radiation” could be generated by absorbing/emitting gases.
Back radiation – as observed – is being emitted from water, ice or other aerosols exclusively.
“holds only in the case of constant gas pressure” — why would this be the case? How can you exclude, for example, that the temperature rise still occurs even when the pressure is not constant because, for example, the volume does NOT also rise by enough to offset the increased heat and pressure?
Matt 3.
Sorry, I should not have used the word pressure but “gas density”, which reduces to zero with increasing altitude thus creating an Anisotrophy of the mean free paa of radiation interacting witth absorbing/emitting gases.
As a result radiation emitted at the Earth´s surface keeps its general direction into space. LW radiation towards the surface however is being returned into space or will be absorbed in liquid or solid matter.
This phenomena, not being recognized, leeds to the present misinterpretation of spectra and the actual back radiation caused by liquid and solid matter alone.
u. Wolff:
Take a look at The Amazing Case of “Back Radiation” – Part Two where you can see the spectra of DLR or “back radiation”.
Radiation from the atmosphere depends on the amount of each type of radiatively-active gas, the temperature profile through the atmosphere, and the strength of each spectral line of each gas. And of course the Planck function.
Your statement claiming that no back radiation can be generated by absorbing/emitting gases in the Earth’s atmosphere is incorrect. It does not follow from your preceding statements.
You can see the equations of radiative transfer – absorption and emission – in Atmospheric Radiation and the “Greenhouse” Effect – Part Six.
SoD. The spectral measurements are misinterpreted.
My previous statement adresses the Anisotrophy of the mean free path of relevant LW radiation as a consequence of the gas density reduction towards space,
Therefore LW radiation emitted at the earth´s surface and reacting with absorbing gases will keep its general direction towards space if not scattered into water, ice or other aerosols.
The direction of respective LW radiation emitted by water, ice and other aerosols towards the earth´s surface and interacting with absorbing gases against increasing gas density will be reveversed.
These effects – well known in nuclear technology – are neglected as well as the influence of particle size of liquid and solid matter on the energy fluxes including the Earth´s albedo.
Therefrore your recomendation lacks relevancy.
u. Wolff:
Are you saying gases like CO2, water vapor and methane at atmospheric temperatures (210-300K) don’t emit longwave radiation?
But these gases do absorb longwave radiation?
How is the spectra of DLR for Antarctica misinterpreted? That big peak at 15um matching the emission spectra of CO2 for that temperature.
u. Wolff:
SoD stated :. “Are you saying gases like CO2, water vapor and methane at atmospheric temperatures (210-300K) don’t emit longwave radiation?
But these gases do absorb longwave radiation?
How is the spectra of DLR for Antarctica misinterpreted? That big peak at 15um matching the emission spectra of CO2 for that temperature.”
The reply:The gases CO2, water vapor and methane absorb and emit longwave radiation!
The spectra of DLR for Antarstica are misinterpeted, ignoring the strong influenze of the Anisotrophy of the mean free path on the direction of radiation flow in the atmosphere.
In an attempt to underständ “that big peak at 15um” you have to recognize
that outgoing radiation of that wavelength is (nearly completely) beiong absorbed in solid and liquid matter, whereas radiation emitted by that matter towards the Earth´s surface will be “back radiated” towards space.
.
I think there is an easier way to see this without ploughing through all the details of radiative transfer. That is: Wolff’s argument proves only that the “general direction” of radiative flow is outward to space. But that is not as much as he thinks it is. By no means does it prove the total flow is outwards. So we can still say that the general direction if outwards, but some does flow back. That would be the “back radiation”.
Now where this simpler explanation runs into trouble is: some people give figures for this back radiation that is even higher than energy coming in! This, though, is simply poor exposition going all the way back to Trenberth’s famous diagram, which really does make it look like more energy is being radiated from the sky back to earth than coming in from the Sun, and is an aspect of his diagram I have never seen explained well.
Matt J. says
“Trenberth’s famous diagram, which really does make it look like more energy is being radiated from the sky back to earth than coming in from the Sun”
Strangely enough this aspect does not concern me.
There are many physical oscillating systems like;
A tuned parallel LC circuit
Or more simply a child on a swing
Where the make up energy from the supply is a lot less than the energy circulating in the system.
What is required is storage mechanisms within the system.
Page 982 of the Kramm & Dlugi paper shows such a viable system.
Does a greenhouse gas model do the same?
DeWitt Payne
Your statement – “Lowering emissivity, whether by using LW IR opaque windows in a greenhouse or adding IR absorbing gases to the atmosphere has exactly the same result, higher temperature.” – holds only in case of constant gas pressure wiithin the volume considered.
However,this condition does not apply for the Earth´s atmosphere..Therefore no “back radiation” could be generated by absorbing/emitting gases.
Back radiation – as observed – is being emitted from water, ice or other aerosols exclusively.
If downwelling IR radiation were being emitted by solids or liquids in the atmosphere, then it would not have the structure observed for clear sky radiation. That structure can be reproduced with high precision using line-by-line radiative transfer models like LBLRTM and with good precision with moderate resolution band models like MODTRAN. The spectra of cloudy skies has the Planck spectrum. The spectra of clear skies does not.
[...] Comments « Kramm & Dlugi On Illuminating the Confusion of the Unclear [...]
SOD
Sorry if this is a bit off topic
1 if the atmosphere of a planet were 100% non-GHG would there be radiation from the conductively warmed atmosphere? I know that BB radiation would be emitted from the planet surface, but not intercepted by the atmosphere and therefore lost directly to space.
Do ALL bodies above 0K radiate? therefore does e.g. O2 / N2 radiate?
2 Why is the DALR so important to every body in this discussion as it only refers to an artificial situation where a parcel of air moved between gravity generated pressure differences (with no interchange of energy). When the parcel is static there is nothing to maintain the temp difference and thermal mixing will occur leading to uniform temperature with altitude – (if this were not the case free energy could be extracted from the column!). Also, to maintain number of molecules at each altitude what goes up must come down! So energy transfer is minimal (zero).
Surely the only relevant lapse rate is the environmental lapse rate (a very variable -6.5K/km). This is used to explain why a mountain top is cooler than a valley (by claiming the proximity of the temperature source (the ground) is more distant at the top). This does not reference pressure differences in the literature I have seen. But what happens with a vast plateau at 1km altitude – will this be 6.5K cooler than the sea level land? If so why?
thefordprefect:
1. Negligible radiation from the conductively-warmed atmosphere from O2 and N2.
You can see the comparison of the strength of the spectral lines for different gases at The Amazing Case of “Back Radiation” – Part Two under the subheading Properties of Gases – Absorption and Emission. Perhaps someone somewhere has worked out what a column of an N2/O2 atmosphere at current temperatures would emit. Maybe 1 mW/m2? I’m guessing.
2. The DALR is one piece of the puzzle. Equally important is the moist adiabatic lapse rate, which is variable depending on the amount of moisture and the temperature.
The relevant lapse rate is – as you say – the actual lapse rate. But the theory around dry and moist adiabatic lapse rate is what helps explain the environmental lapse rate.
The vast plateau at 1km altitude – will it be 6.5K cooler than sea level ? – sounds like the kind of question that could occupy a discussion panel for a long time. It depends on all kinds of factors.
thefordprefect:
If higher temperature molecules move up and lower temperature molecules move down you have conservation of mass. And you have conservation of energy.
But you don’t have constant energy vs height.
In fact, what happens when convection takes place – say with a heated plate at the bottom of a water tank – is that warmer water moves up and colder water moves down.
This redistributes energy.
Here is a nice page with video link showing an experiment on this topic. There are other great videos via links at the top of this page. It accompanies the excellent Marshall & Plumb (2008) textbook.
Thanks for that …. BUT!!
at 10k metres the temp is set by the lapse rate and the temp at 0m
so a parcel of air moving from 0 to 10km will loose thermal energy and gain potential enregy ending up at the same temp as the other stuff at 10km
an in reverse from 10km to 0m so unless you assume that the parcel is heated without heating the other parcels no heat will be transported..
I assumed that if a 100% insulated row of air were suddenly turned to a column of air then the lower air would be compressed and heated and the upper rarified air would cool to maintain energy balance.( low air high T but low potential energy; high air low T but high potential energy) This would give the adiabatic lapse rate. But then will not the air mix to eventually give a uniform temperature? But then you have medium temp with high potential energy and medium temp with low potential energy. Thi9s seems wrong?
Also I know you have said that N2 and O2 do not emit radiation but what is the difference between a gas and a solid when it comes tho blackbody radiation. – Most books talk about all matter above 0K emitting BBradiation. So why not non GHGs. I KNOW that no narrow emissions from non-GHGs will occur – non is captured and none is emitted. But non GHGs can be warm, they are matter, so do the not radiate over the usual BB spectrum?
I just cannot find and definitive statement that says gasses do not have a black body radiation!
of interest:
http://www.ssec.wisc.edu/library/coursefiles/03_abs_emiss_ref.pdf
The physics of atmospheres By John Theodore Houghton
preview:
http://books.google.co.uk/books?id=K9wGHim2DXwC&printsec=frontcover&dq=%22The+physics+of+atmospheres+By+John+Theodore+Houghton%22&hl=en&sa=X&ei=eeEHT9LGMseo8QPrlayJCA&ved=0CDUQuwUwAA#v=onepage&q=%22The%20physics%20of%20atmospheres%20By%20John%20Theodore%20Houghton%22&f=false
thefordprefect:
My point (about movement of fluids of different temperatures) was to clear up something that can cause confusion.
If the environmental lapse rate matches the adiabatic lapse rate for the parcel of air then you are (kind of) correct.
There is always potential for confusion with the sign of lapse rates and what “greater than”, “less than” means in this context, so I will first work by way of example.
If the environmental temperature drops by 6K/km and the adiabatic lapse rate is a reduction of 10K/km then the atmosphere is stable to convection. This means that a parcel displaced vertically will have a restoring force back to its original location. This is true right up to the point where the environmental temperature drops by 10K/km. So convection won’t happen. So the question about movement of energy is not relevant.
If the lapse rate of the parcel is greater than the lapse rate of the environment (e.g., lapse rate of the parcel is -4K/km due to the moisture content and temperature while environmental lapse rate is -6K/km) then convection takes place because a displaced parcel experiences a continued force in the direction of motion.
In this case the change in temperature of the parcel is, by definition, not the same as the change in temperature of the environment and so energy has moved location. (The vertical profile of energy has changed).
Does this make sense?
thefordprefect:
Many people have asked the same or similar question so I will try and write an article about it soon.
But in brief, pending my article, liquids and solids are quite different but don’t anyway emit as a blackbody (emissivity = 1 over all wavelengths). Instead solids and liquids tend to have continuous emission of radiation with non-unity emissivity.
Gases are different. They have lines of absorption and emission at specific energies. These lines are broadened by “natural line broadening” due to the uncertainty principle, and more importantly by Doppler and Pressure (collisional) broadening. See Understanding Atmospheric Radiation and the “Greenhouse” Effect – Part Nine for a little on the energy changes for absorption/emission and the broadening mechanisms.
Here’s a little thought.
(using broad band radiation to indicate a coloured form of black body radiation)
Most people say broad band radiation occurs from all “stuff” above 0K temperature. But what is the difference between solid and gaseous stuff. E.G. take solid CO2. I would assume this gives broadband radiation as the temp is above 0K and it is a solid. This heats a bit and sublimates to CO2 gas. Now all of a sudden it only radiates at certain frequencies – why? Is the total radiation the same in gas/solid cases.
Liquid nitrogen is similar. I assume BBradiation when a liquid(?) but then on turning to gas NO radiation will be emitted.
Just does not sound logical – but then I’m no physicist!
TFP,
To get IR emission you need a resonant frequency in the force fields linking atoms. Solids and liquids have complex interacting forces between molecules. Gases don’t. It comes down to the oscillations excited on discrete collisions. Symmetric diatomic molecules have only one mode, stretching, and its frequency is not in the IR range. They are too stiff. Polyatomic noledules have bending modes etc.
Nick,
It’s not that the frequency of the stretch mode is too high for diatomic molecules, the key is the symmetry. You need a change in the dipole moment with the stretch. You don’t get that with symmetric molecules, at least for the electric dipole moment. In fact, the vibrational level of nitrogen is quite close to the asymmetric stretch vibrational level of CO2 at 2349 cm-1 needed for a CO2 laser at ~10 μm. That’s why N2 is part of the gas mixture for CO2 lasers. The laser transition is either to the second bending level which gives a laser wavelength of 9.4 μm or to the first symmetric stretch level at 1388 cm-1 which gives a laser wavelength of 10.4 μm.
CO has bands at 1948 – 2028 cm-1, 2028 – 2218 cm-1 and 2218 – 2278 cm-1 which puts it barely in the thermal IR. NO has bands at 1700 – 1770 cm-1 and 1770 – 1977 cm-1
Gerhard Kramm:
I would really appreciate it if you can confirm that the points made above, reproduced here below (in reverse), are correct.
You will assist the multitudes of confused people who read blogs but not textbooks and have become convinced that by definition atmospheric radiation either does not exist or cannot affect the surface temperature of the earth.
I am trying to avoid very formal statements and equations because this just confuses a lot of people.
————
i) cool objects do radiate towards hot objects
ii) hot objects can and do absorb the radiation from cool objects (Note 1)
iii) radiation absorbed from cooler objects by hotter objects affects the internal energy of the body, and therefore, usually the temperature. 1J absorbed from a colder body has exactly the same effect on internal energy as 1J absorbed from a hotter body – there is absolutely no distinction. Radiation absorbed from cool bodies by hotter bodies slows down the rate of heat loss from the hotter body because more radiation is transferred in the other direction.
Note 1: The proportion of radiation absorbed is a function of the absorptivity of the receiving body and of the geometry (the view factor).
And absorptivity is a material property which depends on wavelength and direction.
scienceofdoom on January 5, 2012 at 8:22 am
The first and second boundary condition are given non-local (the first, however, already), but globally. This places even on Kramm fixed Page 992: “We share Fortak’s [31] argument that the outgoing emission of infrared radiation only serves to maintain the radiative equilibrium at the TOA (see Eq.4.1).“
„If the temperature profile of the atmosphere is accurately known this provides the required information to calculate the solution.” The solutions cause themselves mutually. The integral of the change of the energy fluxes must be zero. Especially without further energy flows are only for the radiation fluxes must be the integral over all wavelengths and angles zero.
“If not the temperature profile of the atmosphere is known then a convective model provides a useful estimate.” It’s not enough, because the change in the tropopause from a pure convective model is not visible.
“I do not understand what you are saying here. What reversal of cause and effect?” By changing the concentration of greenhouse gases is at first the divergence is not zero, but only by changing the temperature profile, it comes back to the divergence is zero. The zero point of divergence is likely to believe that there can be no change in temperature, or words to warming are wrong. For even in places with radiative equilibrium occurs at a higher concentration of greenhouse gases to cool.
u. Wolff,
Apparently you don’t understand the physics of absorption and emission of radiation by molecular gases. I highly recommend Grant Petty’s book “A First Course in Atmospheric Radiation”. It’s available from the publisher http://www.sundogpublishing.com/shop/a-first-course-in-atmospheric-radiation-2nd-ed/
A photon that is absorbed does not retain its direction. It’s absorbed. It no longer exists. When an excited molecule, which is almost never the same as the absorbing molecule, emits, the emission direction is completely random. It’s (almost) equally likely to be upward to space or downward to the surface. Almost, because the geometry is spherical so upward is very slightly more probable than downward. The reason that it is almost never the same molecule that emits is because collisional energy transfer is several orders of magnitude more likely than radiative energy transfer for an excited molecule. This condition is called local thermal equilibrium and is required for Kirchhoff’s Law (emissivity = absorptivity) to be applicable. It’s valid to at least 30 km altitude for most gases and even higher for CO2 (> 90 km).
Dewitt Payne,
Apparently you don´t understand the facts, I referred to:
A multitude of emissions is called isotrop, if all angles are equally probable. This applies more or less to the LW emission of molecules we are talking about here.
Wiithin the Atmosphere the average distance to the next absorbing molecule is increasing with decreasing gas density (towards space), it is decreasing mith increasing gas density (towards the Earth´surface)
Therefore the mean free pass of “photons” becomes anisotropic,
As a result the direction of radiation (or energy) flow will behave according to my previous explanation:
LW radiation emitted from the Earth´surface will pass these absorbing gases, whereas LW radiation towards the suirface will be “back radiated” towards space.
This behaviour is well known at least in Physics applied in the field of nuclear technology. Therefore the “CO2-water vapor-green-house effect” should be filed under “—-”! [Moderator's note - Please read The Etiquette]
Why will it pass those absorbing molecules? Does the Beer-Lambert Law not apply to the atmosphere?
For clear sky US 1976 standard atmosphere, only about 15% of the radiation leaving the surface is transmitted directly to space. The rest is absorbed. In the frequency range 640-690 cm-1 effectively 100% is absorbed by CO2 molecules within 300 m. That means looking up in that frequency range, the atmosphere is effectively a black body at very close to the temperature of the surface. And that’s just for CO2. Most of the absorption and emission is caused by water vapor. At 15 C and 75% relative humidity, water vapor absorbs 100% of radiation in the range 0-400 cm-1 and 100% of LW radiation with frequencies greater than 1400 cm-1 and a lot of what’s in between. And that’s just for a path length of 500 m. Add in CO2, methane, nitrous oxide and the other ghg’s and quite a bit of the energy emitted by the surface is absorbed within 500 m of the surface. Since absorptivity = emissivity at local thermal equilibrium, the atmosphere will appear to be a black body at those frequencies and emit according to the Planck function. That radiation will reach the surface for the same reason as the radiation from the surface is absorbed.
You can hand wave all you want about anisotropy, but it isn’t relevant over that short of a distance. Yes, it does mean there will be a net flow of radiation outward, but most of that radiation will originate at altitudes much higher than the surface. At 667 cm-1, the effective emission altitude to space is greater than 30 km. At the surface looking up , it’s ~20 cm.
@ DeWitt Payne January 5, 2012 at 3:10 pm
DeWitt Payne times have you estimated temperature difference, when about 300 W / m² should be transferred between two black bodies? Between the window and the absorber area see Gerlich (http://arxiv.org/abs/0707.1161 page 30 table 9). The car interior is a kind of Wood-chamber. The convection inside the measuring chamber plays the main role.
Convection and conduction play a role in the interior of the car because the body is opaque to LW IR and the windows are nearly opaque. But not the sole role. The interior surface that absorbs the solar radiation will be hotter than the air in the car. That surface will radiate and that radiation will be absorbed by the interior surfaces not directly exposed. So those surface will be warmer than they would be if convection were the only means of heat transfer inside the car. Most of the convection will occur as the interior of the car is warming. There won’t be much interior convection when steady state is reached. The exterior of the car also radiates according to its temperature, which will be higher than the ambient temperature. If the windows were LW IR transparent, the interior of the car would still be hotter than ambient, but lower than a similar car with LW IR opaque windows because some of the radiation from the interior surfaces will be transmitted outside the car rather than being absorbed by the windows.
Think about a home oven with a window in the door. Do you really think that if the window were transparent in the thermal IR but still had the same thermal resistivity as an IR opaque window that it would require the same amount of power to maintain a steady temperature as an oven with a window that is LW IR opaque?
Let us assume that the incident on the absorber solar radiation would be 300W / m² and the inner surface of the car would 30°C (303K) – then would then in steady state, the absorber surface assume a temperature of 342K (69°C) when the radiation only after a page is done (other side insulated). The incident radiation in the sun is even higher (approximately 700W / m²). Since the temperature of the absorber would have 380K (107 ° C) reach. If the bodies are not perfect black, the temperatures are even higher.
These temperatures are not nearly reached. Since there is no magic, lower temperatures are possible only with a high proportion of non-radiative heat transfer. Because poorly heat-conducting materials are used, the non-radiative heat transfer within the chamber can be done mainly by convection.
Jochen Ebel,
Sure they are if the insulation is good enough and even higher if there are multiple layers of IR absorbing material. Direct normal solar insolation at local noon is more like 1000 W/m² than 700.
See this graph from a box with heavily insulated walls and three layers of IR absorbing windows: http://i165.photobucket.com/albums/u43/gplracerx/multilayerbox1.jpg
Temperatures are in degrees C measured with exposed bead type K thermocouples
Channel 1 ambient air
Channel 2 bottom surface perpendicular to incident solar radiation
Channel 4 2.4mm glass ~3 inches above and parallel to the bottom surface
Channel 5 2mm clear polycarbonate ~3 inches above and parallel to the glass window
Channel 6 2mm clear acrylic ~3 inches above and parallel to the polycarbonate
That experiment didn’t run long enough to reach steady state. A later experiment had a bottom surface temperature greater than 170 C.
This graph is for boxes with a single layer window with heavily insulated walls:
http://i165.photobucket.com/albums/u43/gplracerx/heavilyinsulatedplasticboxes.jpg
In this case, the box temperature is the air temperature ~1 inch above the bottom surface with that surface oriented perpendicular to incident solar radiation. The temperature of the bottom surface would be higher.
Channel 1 ambient air
Channel 2 0.8 mil polyethylene shrink wrap windowed box air temperature
Channel 3 2.4mm glass windowed box air temperature.
DeWitt Payne,
Apparently it is You, who is missing the point:
The spatiol distribution directions of emissions of “potons) are more or less isotgropic. /The space angle of 360 degree.)
Not so the distribution of distances to next absorptions in the atmosphere, where the gas density varies between a maximum to zero.
Therefore the probality for radiation emitted at the surface to return to its origin is essentially zero.
The same holds for the probality for any radiation being emitted by liquid or solid matter in the atmosphere to reach the surface of the earth against increasing gas density.
Ignoring this effect in the construction of the CO2-water vapor-greenhouse-effekt removes its foundation. Back radiation does not origin from gas atoms!
Therefore the recommended literature is of rather limited use.
Correction:
DeWitt Payne,
Apparently it is You, who is missing the point:
The spatial distribution of directions of emitted “potons” is more or less isotropic. /into the space angle of 360 degree.)
Not so the distribution of distances to next absorptions in the atmosphere where the gas density varies between a maximum to zero.
Therefore the probality for radiation emitted at the surface to return to its origin is essentially zero.
The same holds for the probality for any radiation being emitted by liquid or solid matter in the atmosphere to reach the surface of the earth against increasing gas density.
Ignoring this effect in the construction of the CO2-water vapor-greenhouse-effekt removes its foundation. Back radiation does not origin from gas atoms!
Therefore the recommended literature is of rather limited use.
Therefore the probality for radiation emitted at the surface to return to its origin is essentially zero.
That’s correct, but for the wrong reason. Reflection or scattering of LW IR radiation by anything in the atmosphere can usually be neglected. Small ice crystals in cirrus clouds do have some reflectivity in the LW IR, though.
Are you seriously arguing that none of the radiation emitted by CO2 molecules a few cm above the surface can reach said surface? The mean free path of CO2 at the peak emission of 667 cm-1 is on the order of 20 cm at 390 ppmv and 1013hPa. All the rest of the radiation in the band has a much longer mean free path. Atmospheric pressure simply doesn’t drop fast enough for your hypothesis to be true. Approximately 90% of the radiation from the atmosphere seen by the surface originates within 500 m of the surface. At that point the pressure has only dropped about 5%.
So the fact that an inexpensive handheld IR thermometer ( Actron CP7876 for example ) pointed at a cloud covered sky reads about the same temperature as the surface (or at all) while the apparent temperature of a clear sky for the same surface temperature is much lower is just some sort of magical artifact? Or the fact that the reading from an IR thermometer straight upwards can be correlated with column total precipitable water ( http://journals.ametsoc.org/doi/pdf/10.1175/2011BAMS3215.1 ) is also caused by something other than the emission of IR radiation by water vapor in the air above the thermometer?
Get a clue!
DeWitt Paine,
“Therefore the probality for radiation emitted at the surface to return to its origin is essentially zero.”
“The same holds for the probality for any radiation being emitted by liquid or solid matter in the atmosphere to reach the surface of the earth against increasing gas density.”
“LW radiation emitted from the Earth´surface will pass these absorbing gases, whereas LW radiation towards the suirface will be “back radiated” towards space.”
Please recognize the following facts:
1. , The mean free path is increasing with altitude from a minimum value at the highest gas density towards “infinty” when the gas density is approaching zero..
2. Visible clouds are not transparent for LW radiation discussed here. (1 kg of water or ice contained in 10 000 kg air over one square meter of the surface have an absorbing surface between 3 – 3000 square meter depending on particle diameters varying between 1 – 0,01 mm)
3. Absorbing gases “back radiate” only distinct wave lengths. Therefore your instrument will register a big fraction of the LW radiation emitted by liquoid and solid matter in the atmosphere. Such gases act as selective filters.
4. The probabilty for “photons” to be “back radiated” to the surface folowing an interaction with absorbing gases decaqys strongly with increasing altitude. Morning fog ist more efficient by ordes of magnitude !!
5. Consider that the intgeraction of solar radtiaon with ilquid and solid matter in clouds and at ocean surfaces is mainly determining the Earth´s albedo, The interaction with LW radiation ist considerably mor efficient. I recommend a look into “geometrical Optics”.
6. As a consequence of the anisotrpy of the mean free pass of “photons” belonging to the “reactable” fraction of LW radiation emtitted at the surface, of the earth these photons are “forwarded” towards space, The bigger fraction is being “scattered” into liquid and solid matter. Als long as these effects are being ignored, the numenbers you quoted lack justification.
SOD: When criticizing G&T and now Kramm for some aspects of their papers, we should realize that it would be nearly impossible to get any aspect of their work on the greenhouse effect published – even if it were mostly correct – in the same journals as your favorite papers by Ramanathan. A successful scientific journal really can’t stand up to the threat that prominent scientists might promote a boycott of their journal and the Climategate emails certainly show that such boycotts were threatened and editors have resigned after skeptical papers were published. Perhaps (probably?) I exaggerate, but it would be unreasonable to deny that skeptics could BELIEVE that this is the situation they face.
What Kramm (and possible G&T) appear to have done is slip their ideas into journals that publish articles of general interest to the physics community. Reading Kramm carefully, I found only about a couple of paragraphs in the main text that directly contradict the IPCC consensus. Kramm didn’t need 25 pages and Milankovitch cycles to present controversial ideas about the greenhouse effect, but they wouldn’t get published in a general-interest journal without most of it. Even worse, the more completely they describe what and why they disagree with the consensus, the more likely the article will be found to be diverted to a specialist journal and die from “gatekeeping”. I hated every moment of struggling through all the extraneous material to try to understand a few vague dense passages contradicting the consensus, but perhaps it was necessary
IMO, this strategy makes for lousy publications and risks inadequate review and revision of the most important content. But this is the only way I’ll learn that observations of the Moon’s mean surface temperature don’t agree with the methods I understand for calculating the earth’s surface temperature without GHGs. Unfortunately, when I reread the Hoovering Incident post so I can blame SOD for the fallacies I picked up somewhere, I find caveats about unrealistic models and no mention of the infamous 33 degK. You do amazing work for a … [picture Kramm holding his nose] … “blogger”.
Frank
Four times I have tried to publish critical remarks concerning the “main stream story” of IPCC in highly accepted so called scioentific “Climate Journals”.-
Four times the articles had been rejected. – When an “”adviser” to the editor flattly stated: “The article of Mr, Wolff must not be published in “….”, – I gave up and published in “Energiewirtschaftliche Tagesfragen” instead :thus at least least forwarding some information in common language to the public domain.
May be the quality of my remarks did not meet the “high standards” of “the CO2 protagonists”, but the readers of my renmarks signalled agreement..
Apparently a scientific discussion of the !atmospheric green house effect” did not take place until today!
By the way, I believe one could well define such effect caused by liquid and solkid matter in the atmosphere leaving the “absorbing gases”.as silent spectators.
“May be the quality of my remarks did not meet the “high standards” of “the CO2 protagonists”, but the readers of my renmarks signalled agreement..”
Newflash: even flat-earth faddists can find “readers of their remarks who signal agreement”. That you found some readers who agree with you means exactly nothing.
BTW: I am not seeing much agreement here with your idea that only non-gases can cause back radiation. Can you take the hint? “Essentially zero” does not mean “actually zero”. Especially not when you have to allow the chance for this “essentially zero” quantity to grow as you integrate over the entire relevant volume — which you do not do.
SoD, Matt J., DeWitt Payne
Physics is observation using mathematical models to correlate data:
The globe is continuously separated from space by visible clouds on about 60 to 70% of its surface. Liquid and solid matter make clouds intransparent for LW radiation emitting continuously LW radiation towards space and surface.(Even air passing the 5% fraction of deserts contains such matter with rather small particle size but having a huge surface area.)
This change of state of water and energy loss create the Tropopause and strongly influence Temperatures and its distributions in Crust and atmosphere.
Interactions of “absorbing gases” with LW radiation fluxes below “clouds” have therefore no potential to change temperatures at the surface of the crust – accepting or ignoring “forward scattering” does not make any difference.
There exist no data from observation which could put the above findings into question.
There is also no indication in climate history that the reduction of CO2 concentration from 25% down to 0,04% at present ever did have any detectable influence on temperatures at the crust´s surface. (During 3 billion years water temperaatures in the oceans stayed between -2 and +30 degC with constant ground temperatures close to +4 degC)
The Model of the “atmospheric green house effect” based on absorbing gases is ignoring these observations, and is not grounded on relevant evidence,
Therefore it is about time to file “another fairy tail” under the subject “Scientific Errors:”
However, apparently “disputing” is the real goal!!
u. Wolff,
I’m not surprised that mainstream journals refused to publish your work.
Indeed. We observe that the molecular gases like CO2 and water vapor absorb and emit radiation with a line structure (water vapor also has significant continuum absorption/emission) at wavelengths in the thermal IR range from 4-100 μm. The wavelengths and line strengths of these transitions can be calculated ab initio as well as accurately measured in the lab and in the field. We also have a mathematical model of radiative transfer in the atmosphere through molecular gases. It’s called the Schwarzchild-Milne equation. That equation can be solved numerically using the vertical temperature and pressure profile of the atmosphere and the partial pressure profiles of the molecular gases. The solution is a spectrum. That spectrum closely matches the observed spectrum from a clear sky.
Yes, ~60% of the surface is covered by clouds at any given time, but 40% isn’t. Also, there is absorption and emission in the atmosphere above the cloud tops that influences how much of the radiation from the cloud tops reaches space. Spectra can also be taken at high altitude and from orbit. Those spectra show structure different from the Planck curve and consistent with molecular absorption and emission even for the cloud covered surface and can also be calculated with good precision and accuracy.
DeWitt Payne,
all articles published in “mainstream journals”includong the IPCC reports ignore the fact, that “at least” 60 to 70 % of the globe are being seperated from space by liquid and solid matter continuously.
This indisputable observation alone puts all claims with respect to the green house effect as speculated to be caused by absorbing gases “ad absurdum”.
Thereore I can fully understand, why “mainstream journals” have to reject my articles and also your reaction concerning my remarks.
My finding is that,realisingf the existance of liquid and solid matter in the atmosphere strongly improves the understanding of observations including spectra.
Absorbing gases as “line absorbers and emitters” may effect spectra, but not at all temperatures of the Earth´crust.
That’s simply wrong. In Fasulo, Kiehl and Trenberth 2009 (http://www.cgd.ucar.edu/cas/Trenberth/trenberth.papers/TFK_bams09.pdf ) including the appendix and references, the word cloud (clouds, cloudiness, CloudSat, etc.) occurs 50 times. And that’s just one article. Lots of the references were about the effects of clouds. I’d agree that Miskolczi ignores clouds when he calculates τ, but then his papers aren’t published in mainstream journals either. The only way you could be this obtuse is to purposely ignore the relevant literature.
u. Wolff, continuing his/her absurd theme so far presented:
If by “ignore the fact” you mean “don’t share your view of clouds and believe that spectra like this one from Antarctica:
is caused by clouds and not primarily by CO2, despite the fact that the emission spectrum of water is very different and this spectrum is also calculated to be almost exactly the same using these “flawed” concepts of climate science.”
- then you are probably correct.
The journals and the atmospheric physicists of the last 50 years don’t share your views.
For other readers – obviously climate science does pay a lot of attention to clouds and the climate impact of clouds and it is a key area of current research.
Journal of Geophysical Research – Atmospheres, just as one example, published 210 articles in 2011 with clouds in the abstract and 91 with clouds in the title.
E.g.
Retrievals of cloud optical depth and effective radius from Thin-Cloud Rotating Shadowband Radiometer measurements
Effects of cloud microphysics on monsoon convective system and its formation environments over the South China Sea: A two‐dimensional cloud‐resolving modeling study
Factors influencing the microphysics and radiative properties of liquid‐dominated Arctic clouds: Insight from observations of aerosol and clouds during ISDAC
On the effect of dust particles on global cloud condensation nuclei and cloud droplet number
Evaluation of cloud‐resolving model intercomparison simulations using TWP‐ICE observations: Precipitation and cloud structure
An assessment of differences between cloud effective particle radius retrievals for marine water clouds from three MODIS spectral bands
The cloud radiative effects of International Satellite Cloud Climatology Project weather states
Toward an Earth Clouds, Aerosols and Radiation Explore (EarthCARE) thermal flux determination: Evaluation using Clouds and the Earth’s Radiant Energy System (CERES) true along‐track data
Cloud radar Doppler spectra in drizzling stratiform clouds: 2. Observations and microphysical modeling of drizzle evolution
Representation of Arctic mixed‐phase clouds and the Wegener‐Bergeron‐Findeisen process in climate models: Perspectives from a cloud‐resolving study
-etc-
Journal of Climate published 26 articles with cloud in the title in 2011 and 93 with it in the abstract:
Response of upper clouds in global warming experiments obtained using a global nonhydrostatic model with explicit cloud processes
Probability Density Functions of Liquid Water Path and Total Water Content of Marine Boundary Layer Clouds: Implications for Cloud Parameterization
Sensitivity of Hadley Circulation to Physical Parameters and Resolution through Changing Upper-Tropospheric Ice Clouds Using a Global Cloud-System Resolving Model
The Distribution of Cloud Horizontal Sizes
Variations in Cloud Cover and Cloud Types over the Ocean from Surface Observations, 1954–2008
Assessing Simulated Clouds and Radiative Fluxes Using Properties of Clouds Whose Tops are Exposed to Space
Computing and Partitioning Cloud Feedbacks using Cloud Property Histograms. Part II: Attribution to Changes in Cloud Amount, Altitude, and Optical Depth
Boundary Layer and Cloud Structure Controls on Tropical Low Cloud Cover Using A-Train Satellite Data and ECMWF Analyses
An Estimate of Low-Cloud Feedbacks from Variations of Cloud Radiative and Physical Properties with Sea Surface Temperature on Interannual Time Scales
Time Scales of Variability of the Tropical Atmosphere Derived from Cloud-Defined Weather States
A Three-Year Climatology of Cloud-Top Phase over the Southern Ocean and North Pacific
Intensification of Precipitation Extremes with Warming in a Cloud-Resolving Model
Examination of POLDER/PARASOL and MODIS/Aqua Cloud Fractions and Properties Representativeness
Major Characteristics of Southern Ocean Cloud Regimes and Their Effects on the Energy Budget
Moist Thermodynamics of the Madden–Julian Oscillation in a Cloud-Resolving Simulation
Relationship of Lower Troposphere Cloud Cover and Cosmic Rays: An Updated Perspective
On the Relationship between Thermodynamic Structure and Cloud Top, and its Climate Significance in the Arctic
Reproducibility by climate models of cloud radiative forcing associated with tropical convection
Longwave 3D Benchmarks for Inhomogeneous Clouds and Comparisons with Approximate Methods
Observed Increase of TTL Temperature and Water Vapor in Polluted Clouds over Asia
-etc-
But I can see why you might have trouble getting your articles published.
SoD, DeWitt Payne
<<<< u. Wolff, continuing his absurd theme so far presented:
..all articles published in “mainstream journals”includong the IPCC reports ignore the fact, that “at least” 60 to 70 % of the globe are being seperated from space by liquid and solid matter continuously..
If by “ignore the fact” you mean “don’t share your view of clouds and believe that spectra like this one from Antarctica: ………is caused by clouds and not primarily by CO2, despite the fact that the emission spectrum of water is very different and this spectrum is also calculated to be almost exactly the same using these “flawed” concepts of climate science.”
- then you are probably correct.
<<<>>
If you would please differenciate between “wheather forcast for several days – which is excellkent physics , the statistics of wheather data attempting to better understand the past (called climate science) – which is excellent scientifical work – and those “Fortune Tellers” claiming to be able to predict (the statistic of) “climate changes.
Adressing the latter group, you are hitting exactly my point !
This list of articles you present confirms my remark concerning the im portance to properly consider liqud and solid matter in the atmosphere.
Only if the dominating influence of such matter on radiation fluxes is being neglected,- what is done – it becomes possible to claim that absorbing gases do contribute (detectably) to temperatures establishing in the crust of the earth. (This is 79 % Oceans with nearly constant temperature distributions and varying volumes only since 3 billion years, 25% humid land areas and 5 to 6 % deserts.)
The content of water und aerosols and its distribution in the atmosphere both are and will be in the future unknown. Fasulo, Kiehl and Trenberth state explicity that “clouds”introduce the biggest uncvertaunty to their attempt to find an energy balance for the Earth. This is underlined also with the multitude of articles you present also) trying to adress local phenomena concerning clouds.
This lack of data makes it impossible to calulate any spectrum at any point where it is measured also. Therefore conclusions drawn from calculations using oversimlified models are meaningless.
Please rekognize the following numbers giving an impression the total surface of water or ice in 10 000 kg of air above one square meter of ground acting and interacting:
The average yearly presipitation is about 1000 mm/m^2. With an average lifetime of droplets from start of condensation until reaching the surface between 3 to 4 days the air columm contains 10 kg of water. The surface of this water depend on the particle diameter d. (Small particals are invisible and have a long “lifeteime”):
Already very big particals with d = 10 mm reach 3 m^2 of surface, with d = 0,01 already 3000 m^2 and in case of very small diameter (carried over deserrt areas) only 10 g of water ore ice in 10 000 kg air can reach 3 m^2.
My Question: Does any of the calculations of spectra you refer to include the respective absorption/emission of LW radiation in the air clumns above ground including forward scattering at absorbing gases?
SoD,
PS. I would like to recommend you to have a look at the macroscopic cross section of CO2 as compared to liquid and solid matter for LW radiation within the volumes of the Tropopause.
You may find respective literature in the field of “Nuclear Technology”, subject “shielding”. (My experimental expirience: says: Water absorbs very efficiently, whereas “absorbing gases” don´t show any detectable effect!)
Thanks for that. I needed a good laugh today.
Water is a very effective shield for neutrons. But we’re not talking about energetic neutrons here, or at least I don’t think so.
DeWitt Payne,
Thanks for that information concerning neutrons, which is very helpful for all people following a business career of fun with nuclear power.
However, one might believe that both, a very thin layer of water or a tiny droplet do absorb LW radiation, which is arriving at its surface, completey and convert it into oscillation energy of molecules, that is to say into heat. Arriving radiation recognizes for the landing prosedure the projection of this matter on a plain area as “cross section”.(Not landing strip!)
Totally independent of this energy conversion business, internal forces squeeze LW radiation out of the liquid or solid matter as long as the temperature exceeds 0 K.The molecule can do that only if the “photon” hits its (microscopic) cross section. The total fraction of LW radiation absorbed than depends on the gas density, on the (macroscopic) cross section. (Such absorption rate can be determined using LASER.)
The energy absorbed will be converted into kinetic enrgy of that absorbing molecule and may remain there from here to eternity, if not forces induced from collision squeeze an emission of radiation in form of a “phpton” out of that very excited moecule, This photon usually looks like a twin brother or sister of the originally absorbed one..
Isn´t that really funny?
The emitted photon frequency will depend on the rotational state of the excited molecule and which vibrational mode is excited. The rotational state of the excited molecule can either go up or down one level or stay the same. It has no direct relation to the frequency of any absorbed photon other than absorbed photons must also have the correct frequency to be absorbed. A 1460 cm-1 photon, for example, is extremely unlikely to be absorbed or emitted by a CO2 molecule because there are very few, very weak absorption lines near that frequency. At a path length of 1,000m, 1 atm of pure CO2 at 296 K would absorb only 0.045% of incident radiation.
The frequency will also vary according to Doppler and pressure broadening. In the lower atmosphere, pressure broadening dominates. Lots of molecules are in an excited state at any given time. For the bending vibration mode of CO2, ~3% are in the excited state at a temperature of 300K. However, only a small fraction of those molecules emit radiation. The rest are de-excited by collision with other gas molecules before they can emit. The amount of radiation emitted from a given volume of gas has no immediate relation to the amount of radiation absorbed. In the absence of absorbed radiation, emission would cause the volume of gas to cool.
SoD
“u. Wolff, continuing his…absurd theme so far presented….:
The journals and the atmospheric physicists of the last 50 years don’t share your views.”
Summarizing in brief what is beeing adressed as being “absurd”:
Absorbing gases can neather “back radiate” nor reduce the size of an “atmospheric window” for LW radiation (within the limits of sensivity of instrumentation available) becaujse of “forward scattering”.
The atmospheric window is closed to nearly 100 % by liqid and solid matter.
Such matter becomes visible only in clouds, when part of visible solar radiation is being scattered or reflected into space mainly because of the phenomenon of “total reflection” well known from Geometrical Optics.
A comparison of likely quantities and particlke sizes of water, ice and other aerosols within the atmosphere make it highly probable, that this matter blocks the way into space with “blue sky” also and even above the small fraction of desert areas. Therefore interaction of absorbing gases cannot influence enrgy fluxes neather at the surface of the crust nor at liquid and solid matter within the atmosphere.
The use of average values for global surface temperature and other data attempting to determine changes of such surface temperatures using analytical models is absurd. So is an “atmospheric greenhous effect caused by absorbing gases”. Instead liquid and solid matter are creating such effect.
Regard the of following observations:
The average temperature of ocean waters is constant with the exception of its saisonal variation of about 0,5 degC The measured variation of the CO2 concentration in the atmosphere together with the temperature dependence of its soluability in water allow such estimate. The variation of energy input following the uneven distribution of oceans between north and south.explains the finding.
At the land fractions of the crust the daily swing of surface temperatures increases with decceasing humidity (vegetation) since.temperatures follow the heat input according to the time constant of the matter which is absorbing solar radiation.
There is no indication in climate history that the reduction of CO2 concentration from 25% down to 0,04% at present ever did have any detectable influence on temperatures at the crust´s surface.
Since millions of years the distribution of water temperaatures in the oceans ranges between -2 and +30 degC with constant ground temperatures close to +4 degC. Only the quantities of water and ice and spatial distributions have varied during history
More facts and arguments attempting to explain the “real” world had to be published outside the “mainstream journals”.
DeWitt Payne, explainig details:
“The emitted photon frequency will depend on the rotational state of the excited molecule and which vibrational mode is excited. The rotational state of the excited molecule can either go up or down one level or stay the same. It has no direct relation to the frequency of any absorbed photon other than absorbed photons must also have the correct frequency to be absorbed. A 1460 cm-1 photon, for example, is extremely unlikely to be absorbed or emitted by a CO2 molecule because there are very few, very weak absorption lines near that frequency. At a path length of 1,000m, 1 atm of pure CO2 at 296 K would absorb only 0.045% of incident radiation.
The frequency will also vary according to Doppler and pressure broadening. In the lower atmosphere, pressure broadening dominates. Lots of molecules are in an excited state at any given time. For the bending vibration mode of CO2, ~3% are in the excited state at a temperature of 300K. However, only a small fraction of those molecules emit radiation. The rest are de-excited by collision with other gas molecules before they can emit. The amount of radiation emitted from a given volume of gas has no immediate relation to the amount of radiation absorbed. In the absence of absorbed radiation, emission would cause the volume of gas to cool.”
Summary:
Whereas liquid and solid matter is emitting LW radiation continuously, molecules of three or more atomic gases max – if excited – eventually emit a single photon after having properly collided with other molecules, (Didn´t I mention thar already?)
Conclusion:
That is one of the reasons, why it could not be the interaction of “absorbing.gases” producing something which is called “atmospheric greenhouse effect”,by ” Academic Fortune Tellers” – but solid and liquid matter.
Other shortcomings of their story presented in “mainstream journals” are explained not only by Kramm, Dlugy; Gerlich, Tscheuschner, Svensmark but a series of other scientists in papers, being systematically ignored by “The Mainstream”..
on January 9, 2012 at 2:22 pm | Reply
SOD, thefordperfect: SOD wrote above:
“But in brief, pending my article, liquids and solids are quite different but don’t anyway emit as a blackbody (emissivity = 1 over all wavelengths). Instead solids and liquids tend to have continuous emission of radiation with non-unity emissivity.
Gases are different. They have lines of absorption and emission at specific energies. These lines are broadened by “natural line broadening” due to the uncertainty principle, and more importantly by Doppler and Pressure (collisional) broadening.”
I’d be careful about suggesting solids and liquids are fundamentally different from gases in their interactions with radiation. Like optically-thin layers of gas, the emissivity of thin films of solids also depends on their thickness. For example:
http://cp2s.uhp-nancy.fr/Photos/pigeat5.pdf
The Schwartzschild eqn probably applies to electromagnetic radiation moving through any substance; gas, liquid or solid. When electromagnetic radiation has passed far enough through a homogeneous medium that it is no longer changing with distance (dI/dz = 0), what comes out is blackbody radiation (B(lamba,T)) at wavelengths where the absorption cross-section is non-zero and presumably zero intensity at wavelengths where the absorption coefficient is zero. The distance needed to produce a blackbody spectrum is simply much shorter for solids and liquids than for gases, thus we usually think solids and liquids emit blackbody radiation with emissivity that is independent of their thickness. The gaps in the blackbody spectrum for solids and liquids presumably cause emissivity to be less than unity, but I don’t understand why the approximation that emissivity is constant for solid and liquids works as well as it does.
Vibrational and electronic absorption spectra are broadened by some of the same factors as gases. The vibrating atoms are in close contact with other vibrating atoms and translating molecules (liquids) which broadens their energy levels. This appears analogous to pressure broadening for gases. In the hundreds of liquid and solid phase IR spectra I’ve seen, I’ve never seen the splitting caused by changes in rotational energy level resolved, but I’m sure splitting is present. Electronic transitions (visible and UV) are usually very broad because of superimposed vibrational and rotational changes plus broadening from environmental factors, but in the proper environment they probably can be resolved to individual lines for each rotational and vibrational change.
I made a quick search trying to find absorption spectra for solid, liquid and gaseous CO2 or water, but didn’t find anything. They would be illuminating.
Correction to the above: Where the absorption cross-section is zero, materials should be transparent and emit whatever light is coming from behind without change. Looking down at the surface of the earth, this would be the 2.7 degK blackbody radiation filing the universe from the big bang, which seems absurd. Which leaves some questions:
Is the absorption cross-section ever zero?
What phenomena produces emissivity less than one? Does some other physics (scattering?) modify gaps?
Angle dependence of emissivity?
I would say the angular dependence of emissivity is related to reflectivity. Since the sum of absorptivity, transmissivity and reflectivity must equal one, for an opaque solid, absorptivity/emissivity goes down as reflectivity goes up.
u. Wolff,
If excited? There are always some molecules in the exited state at atmospheric temperatures. It’s required by the Maxwell-Boltzmann distribution. A vertical column of the atmosphere from the surface contains the equivalent of 3 m3 of pure CO2 at a pressure of 1 atmosphere and a temperature of 273.2 K. That’s 5.9 kg/m2 of surface area or 8E25 molecules/m2. That means the atmosphere has an absorptivity of very nearly 1.0 in the bending mode band near 667 cm-1. To an observer on the ground, that’s opaque and emission in that frequency range looks like a black body with a temperature close to the surface temperature. From space looking down, the atmosphere becomes opaque in that frequency range near the tropopause, which is much colder than the surface or where the atmospheric emission is from water vapor, which has a scale height about 1/4 that of a non-condensable (at atmospheric temperature and pressure) gas like CO2. That’s why the IR emission spectrum of the Earth from the surface looking up and from 20 km looking down looks like this: http://i165.photobucket.com/albums/u43/gplracerx/PettyFig8-2.jpg Figure 8.2 from Grant Petty, A First Course in Atmospheric Radiation, 2nd edition.
Note the line structure of much of the spectrum. You don’t get that sort of line resolution in the IR from solids or liquids, only gases.
Or to quote from an article of mine:
And that’s just for a 2 mm thick layer of the atmosphere at surface temperature and pressure. The Einstein A21 coefficient for the transition is 1.542/sec and the fraction of molecules in the excited state is 0.039. Emission from a solid or liquid only comes from less than 1 μm below the surface, so the number of emitting molecules in a cubic meter of gas and from a solid with a surface area of 1 square meter isn’t all that different.
DeWitt Payne wrote:,
<>>>
Starting from this point one has to consider, that these “5 kg of CO2″ withiin the column of 10 000 kg of air above 1 m^2 of surface area usually are being mixed with water, ice and other aerosols. From precipitation and estimated lifetime of particles this will be a local quantity around an average value of about 10 kg,
The surface area of this matter depends on the particle size. Its order of magnistude can be estimated to be 1000 m^2.as compared to 3 m^2 “cross section” of CO2.
Therefore (radiation) energy flows will be dominated by interactions with liquid and solid matter, In addion “forward scattering” has to be accounted for.
CO2 – acting as a selective filter – will strongly influence spectra, as being observed..
These facts explain the reasoon, why the interpretation of spectra trying to justify the existance of an “CO2 green house effect” simply is false.
Scattering in the atmosphere by aerosols an particles is a well studied, if not entirely well understood field. Chapters 11, 12 and 13 in Grant Petty, A First Course in Atmospheric Radiation, 2nd edition deal with radiative transfer with scattering.
Show me that with your theory you can reproduce the observed emission spectrum of a sky with no obvious clouds. I’m getting very bored with your hand waving explanations. How about something quantitative?
DeWitt Payne wrote:
“I would say the angular dependence of emissivity is related to reflectivity. Since the sum of absorptivity, transmissivity and reflectivity must equal one, for an opaque solid, absorptivity/emissivity goes down as reflectivity goes up.”
If reflection is the usual cause of emissivity being less than unity, then the absorption coefficient can be non-zero at all wavelengths. Metals. which have very low emissivity and high reflectivity, have free electrons that interact with the electric field of radiation and reflect it. Feynman’s book, QED discusses the interference created when a photon is reflected by the front and back surfaces of glass. It’s later discussed in the context of photons scattering off of electrons. Maybe reflection and the converse phenomena of non-unity emission coefficients are derived from the scattering term that is often omitted from the Schwartzschild eqn.
DeWitt Payne wrote:
<<>>
You misunderstood my remark:
In favour of simplicity I called absorpion/emission at “absorbing gases” scattering because the process is isotropic and frequencies are not changed signifcantly.
Particals absorb any LW radiation and convert it into heat while emittiing LW radiation with spectrum and intensity depending on temperature and emissivity (= 0,99 for water and ice).
I did get already “very bored” looking at your calculational model including the conclusions. Therefore I tried to draw your attention to the fact, that the “transparent blue sky” is an illusion, I did do this quantitatively as far as possible concerning particles, whose existance you had ignored. It is my understanding that – according to “Etiquette”- it would be your duty to correct your !theory”.
However, being a phxsicist I could not even consider to use such mathematical model since – in addition to other shortcomings – experimental data required are not abailabe, neither on the spectrum of emission at the crust´s surface,nor on the spatial distribution of particles within the atmosphere.
I strongly recommend you to consider, that it is liqid und solid matter in the atmosphere producing an effect, which on could call “atmospheric green house effect”. But that would require to forget the “mainstream” jokes.
DeWitt Payne wrote,
“Scattering in the atmosphere by aerosols an particles is a well studied, if not entirely well understood field. Chapters 11, 12 and 13 in Grant Petty, A First Course in Atmospheric Radiation, 2nd edition deal with radiative transfer with scattering.
Show me that with your theory you can reproduce the observed emission spectrum of a sky with no obvious clouds. I’m getting very bored with your hand waving explanations. How about something quantitative?”
You misunderstood my remark:
In favour of simplicity I called absorpion/emission at “absorbing gases” scattering because the process is isotropic and frequencies are not changed signifcantly.
Particals absorb any LW radiation and convert it into heat while emittiing LW radiation with spectrum and intensity depending on temperature and emissivity (= 0,99 for water and ice).
I did get already “very bored” looking at your calculational model including the conclusions. Therefore I tried to draw your attention to the fact, that the “transparent blue sky” is an illusion, I did do this quantitatively as far as possible concerning particles, whose existance you had ignored. It is my understanding that – according to “Etiquette”- it would be your duty to correct your !theory”.
However, being a phxsicist I could not even consider to use such mathematical model since – in addition to other shortcomings – experimental data required are not abailabe, neither on the spectrum of emission at the crust´s surface,nor on the spatial distribution of particles within the atmosphere.
I strongly recommend you to consider, that it is liqid und solid matter in the atmosphere producing an effect, which on could call “atmospheric green house effect”. But that would require to forget the “mainstream” jokes.
SoD,
Scanning this platform, I found in “Understanding Atmospheric Radiation and the “Greenhouse” Effect – Part One” the following “key statement”:
“Each layer in the atmosphere absorbs radiation from below (and above). The gases that absorb the energy share this energy via collisions with other gases (thermalization), so that all of the different gases are at the same temperature.
And the radiately-active gases (like water vapor and CO2) then radiate energy in all directions”.
This statement is correct, however it is incomplete and therefore misleading and creating confusion in science and also a strong negative impact on thje efficient utilisation of ressources within the human community..
Ignoring the impact of liquid and solid matter within the atmoshere on energy fluxes means hiding the fact that this matter thereby alters and includes any potentioal influence of said gases on the enthalpy of the Earth´s crust (to any detectable extent).
Said gases function as “selective filter” for outgoing LW radiation having a strong influence on the spectrum of outgoing radiation only.
This statement summerazis my contribution to this post not leaving room for critics concerning the conclusions drawm by Kramm & Dlugi with the exception that this article does not adress the role of the “changes of state” of water.
In future I will just add it to the penultimate section:
“No explanation of radiation would be complete without people saying that this argument is falsified by the fact that convection hasn’t been discussed. Just to forestall that: Convection moves heat from the surface up into the atmosphere very effectively and cools the surface compared with the case if convection didn’t occur.”
I can update this along with a complete list of all other factors pertaining to climate science as not mentioning all of these factors in an educational article on one subject clearly indicates the author is denying the existence of all these other effects.
You have still to explain the Antarctic spectrum which is totally unlike the spectrum of water.
I pointed you to it on January 5, 2012 at 3:09 am and you simply said:
And after citing your view of the world you finished up with:
This is a claim, not a proof.
The paper, which is also cited in that article, shows that the calculations (which use the radiative transfer equations) match the measurements.
If you continue to ignore the burden on you to defend your amazing claim and explain why theory as described in climate science matches measurement, don’t be surprised if I ignore you.
SoD,
Therefore the temperature difference between matter emitting energy into space and the crust would have to increase, if the energy flux from convection,(including heat of condensation and sublimation of water) is reducing.
The size of such temperature difference depends strongly on quantity, shape, distribution and lifetime of liquid and solid matter in the atmosphere.
I believe that any “atmospheric window” left open by this matter is very small thus creating something, which I would call “atmospheric greenhouse” effect.
Concerning my understanding of the “Antartic spectrum” here the following remarks:
The HITRAN data quantify the absorption “cross section” of absorbing gases. Such absorbing molecules – being excited following absorption – would emit radiation into the space angle of 360 deg,, Radiation is being diverted into the waalls of the apparatus.
The same happens to radiation passing a mixture of water vapour, CO2 and liqud/solid matter in the atmosphere. Radiation of certain frequencies will be diverted, absorbed by solid/liqid matter and therefore will be missing at the exit of radiation.
Guessing the spectrum of the “entering” radiation properly and using HITRAN data, the calculation of spectra et the exit matching measured spectra should not be a big deal..
Unfortunately such spectra don´t provide informnation on energy fluxes.
SoD writes:
You have still to explain the Antarctic spectrum which is totally unlike the spectrum of water.
“I pointed you to it on January 5, 2012 at 3:09 am and you simply said:
SoD. The spectral measurements are misinterpreted..
And after citing your view of the world you finished up with:
..Therefore your recomendation lacks relevancy.
This is a claim, not a proof.
The paper, which is also cited in that article, shows that the calculations (which use the radiative transfer equations) match the measurements.
If you continue to ignore the burden on you to defend your amazing claim and explain why theory as described in climate science matches measurement, don’t be surprised if I ignore you.”
Sorry, that my brief statements were causing a misunderstanding.
My “claim” has been and continues to be that proof for the existance of an atmospheric green hous effect caused ba “absorbing gases” is still missing.
Abilities to calculate local spectra do not alter this situation. Therefore imy remark, that the list of articals treating spextra lacks relevancy concerning the missing proof..
:
To my opinion, the arguments of Mr.Wolff are right. Lambert-Beer´s Law treading all optical phenomena – also absorption, emitting and scattering of radiation – along a given path. If one increases the concentration e.g. CO2 the path will be correspondingly reduced. This path for practical total absorption at the present concentration of CO2 will be about 300m. So the small peak of CO2 in the Antarctic spectrum can’t result from the earth surface radiation but either from the sun IR radiation and/or by collision with other molecules in high altitudes.
B. Stadler,
That’s a jumble of words with little correspondence to physics theory or measurement.
If one increases the concentration, e.g., CO2, the emission will be correspondingly increased.
This is because molecules that absorb also emit.
The path at what wavelength?
At 15 μm 95% is absorbed in 1m. By contrast, at 17.4 μm only 20% is absorbed in a path through the whole troposphere. Just as one example.
You can see the transmittance profile across the whole spectrum of absorption in figure 15 of Understanding Atmospheric Radiation and the “Greenhouse” Effect – Part Nine
The small peak in the Antarctic spectrum is from the atmosphere not from the surface radiation. This is because it is measured by an instrument pointing up at the sky.
When you say “..from the sun IR radiation..” in reference to a measured peak at 15 μm you helpfully indicate that you have not understood the subject at all.
Have you done the calculation of solar intensity at 15 μm?
Here is mine, the linear graph for the sun overhead with an albedo of 30%:
Note the big bump at 15 μm..
The log graph:
See the big 15 μm bump..
And the close resemblance to the Antarctic spectrum, where, in any case, the sun is nowhere to be seen:
So first, calculate the azimuth angle of the sun at 75′S on May 1st and secondly, calculate the resulting spectral intensity at 15 μm / 667 cm-1.
You will find it is incredibly tiny, and a lot lower than the measured spectrum.
That’s why opinions are of so little interest on this blog.
Instead, theory and experiment.
SoD, B. Stadler,
At first thanks for accepting the arguments concerning: “The atmospheric Greenhouse Effect” as being caused by liquid and solid matter within the atmosphere not leaving room for any detectable participation of CO2 and water vapour.
Second, Stadler quotes – “.If one increases the concentration e.g. CO2 the path will be correspondingly reduced” -
This is trivial because the mean free path for any radiation between emission and absorption depends simply on the density of gas molecules having an absorptivity for that very wave length. For CO2 and water vapour the mean free path has a minimum at the crusts surface and increases to “infinity” with icreasing altitude.
The “cross section” (beeing a prcticable measure for the specific absorptivity) is different for different wave lengths of passing radiation. Therefore in gases of given density the mean free path for radiation (photons) depends on the wave length also.
Spectra (measured or calculated) do not allow conclusions concerning energy fluxes. Therefore the use of “The Antarctic spectrum” is nothing but a “straw” used in discussion to hide the nonexistance of any detectable influence of CO2 and water vapour on temperatures of the earths crust.
To SoD & U. Wolff
From the earth at a certain surface temperature you will have in a given spectral range a limited amount of energy flux. If you increase the content of CO2 you can’t increase the amount of radiation energy. if one has saturation. In the satellite spectrum you only. can see a single relative (unresolved) sharp line, no excessive side bands You should consult the work of Heinz Hug (May 2007) about measured spectra of CO2 (Die Klimakatastrophe – ein spektroskopisches Artefakt?) and his commends.
When observing from space, the peak in the center of the CO2 band comes from the stratosphere. That’s because, unlike the troposphere, temperature increases with altitude in the stratosphere. The stratosphere is also optically thin. Go to the Archer MODTRAN site: http://forecast.uchicago.edu/Projects/modtran.html , set the sensor altitude for 30 km looking up. Calculate the spectrum. You will see the spectrum for CO2 and ozone. There will be a big spike in the center of the CO2 band from the principal emission lines at 667 cm-1. Now set the sensor for 17km (at the tropopause) looking down. There is no spike and the trough is very deep. If you want something that looks more like the Antarctic, select subarctic Winter as the locality.
To Dewitt Payne, Stadler
“Now set the sensor for 17km (at the tropopause) looking down. There is no spike and the trough is very deep. If you want something that looks more like the Antarctic, select subarctic Winter as the locality.”
Here the explanation again:
In “HITRAN” CO2 molecules – being excited following absorption – would emit radiation into the space angle of 360 deg,, Radiation is than being diverted into the walls of the device contributing massive to the extinction..
The same happens to radiation passing a mixture of water vapour, CO2 and liqud/solid matter in the atmosphere. Radiation of certain frequencies will be diverted, absorbed by solid/liqid matter and therefore will be forming a very deep ttrough- of radiation in an altitude of 17 km above ground.
It may be a very interesting subject, discussing spectra in volumes into which the energy supply is being provided by energy fluxes in parallel to the surface almost completely. However, the orchestra playing the “Atmospheric Greenhouse Effect caused by liquid and solid matter melody” is located around the equator!
B. Stadler:
The atmosphere radiating towards the earth (the thing being measured as the DLR in Antarctica) does have a maximum spectral intensity.
This is defined by Planck’s law. Therefore, for a given temperature of the atmosphere the spectral intensity has a maximum that we can calculate.
We find that emission of thermal radiation never exceeds Planck’s law, which is why it is called “Planck’s law” and not “Planck’s idea that got disproved”.
So, back to the topic at hand, for any radiatively-active gas, as we keep increasing the concentration, eventually the emissivity at a given wavelength (in the vicinity of a spectral line of that radiatively-active gas) will get very close to 1.00.
[Emissivity(λ) = 1 - e-τ(λ), where τ(λ) = optical thickness at wavelength λ ]
So you are kind of correct “you can’t increase the amount of radiation energy” but that is well known and doesn’t disprove what I have already explained. It is consistent with what I have already explained.
And so now it is time for you to provide some kind of calculation that demonstrates whatever hypothesis you would like to propose.
I have put forward a calculation. I have even shown most of the derivation, which comes from fundamental physics and has been well-known and accepted for 60 years – Atmospheric Radiation and the “Greenhouse” Effect – Part Six. And the authors of the paper from which the Antarctic DLR spectrum comes have shown a calculation using the theory that matches the experimental result.
So please, state your theory and be specific. Take a long long look at the article already cited and explain which of the formulas you do not accept. Explain which ones are wrong and why they are wrong. Write down and explain your formulas.
Or, using the formulas accepted for 60 years in physics, show how it is that you can get the correct DLR spectrum.
Don’t write down the opinions that you have because they are not interesting. Science is not about opinions.
And as a special service, here is the maximum spectral intensity possible from a number of given temperatures (220K through to 300K), as a function of wavenumber and in the exact same units as the spectrum from Antarctica:
And compare with Antarctica:
Surprisingly, the emission of radiation from the atmosphere is less than – but not a lot less than – the maximum possible in the vicinity of 650 cm-1 for typical atmospheric temperatures in Antarctica in May.
And just to really help, here is the solar spectrum in this wavenumber region, if the Sun was exactly overhead (which is quite unusual in Antartica in May) and no solar radiation was reflected by the atmosphere – with the same range as the first graph just to make it crystal clear:
And in with a more useful range just so the values can be seen:
And lastly, as I’m sure you want to check all of this for yourself, you can see the equation for “maximum spectral intensity”, aka Planck’s law, as a function of wavenumber here.
And yet more.
Here is the CO2 and water vapor absorption by wavenumber for the same 500 cm-1 – 1700 cm-1 range. (Absorption also tells us about emission because absorptivity=emissivity at the same wavenumber).
Eli takes it you used the 10 cm cell? (water vapor continuum and absorption on rotational lines)
However, being late to the party, and having looked at G&T last night, Kramm’s claims depend on defining thermal radiation as not heat which, as they say is nonsense. For example from G&T
“Fig. 32. A machine which transfers heat from a low temperature reservoir (e.g., stratosphere) to a high temperature reservoir (e.g., atmosphere) without external work applied, cannot exist — even if it is radiatively coupled to an environment, to which it is radiatively balanced. A modern climate model is supposed to be such a variant of a perpetuum mobile of the second kind.”
Denying that a thermally sourced radiative exchange between two bodies is an exchange of heat, well, you got a Humpty Dumpty problem bucky.
Eli Rabett says
“Kramm’s claims depend on defining thermal radiation as not heat which, as they say is nonsense. ”
You should take this issue up with Joel Shore who admits that saying thermal radiation is heat was a mistake.
In the given circumstance heat has the possibility to be changed into work for instance;
Two plates radiating to each other.
If radiative fluxes only are possible then Heat is the net flux and had to be absorbed.
The net flux from higher to lower temperature can be turned into work and is an example of heat transfer.
The radiative exchange from the colder to hotter plate is incapable of being turned into work and so cannot be described as heat
Nah, if you cannot exchange heat by thermal radiation (radiation from a body at temperature T) then the whole sun heats the earth think goes blooey. You might also talk to Chris Essex about that.
And a question for the interested readers to test themselves with – why isn’t the atmospheric emission in the 600-700 cm-1 range exactly the same shape as the profile from spectralcalc.com?
Here’s a clue – optical thickness is linearly proportional to the number of absorbing molecules, but emissivity = 1-eτ (where τ = optical thickness)..
SoD,
if I understand the topic of this discussion correctly, it is adressing the question of an existance or nonexistance of an “Atmospheric Greenhous effect” proposed to be caused by an interaction of absorbing gases with LW radiation emitted from the surface of the earths crust and therefore directing discussion to energy fluxes.
Howeveer the discussion is being diverted towards disputing spectra only:
The existance of CO2 within the atmosphere is well known from the performance of the flora . Changes of its concentration are continuously measured not only in “Mauna Loa”. Emission/absorption of CO2 is well known.
Therefore the spectrum you refer to indicates, that there exist some CO2 also in the air above the instrument.
Experimenal evidence on the intensity of the signal you refer to is missing. Is it microW, mW, W or kW per square meter?
As long as you don´t provide such experimental evidence I have to ignore any conclusions drawn from such spectra concerning energy fluxes or “greenhouse effects”.
Your first comment on this post was on January 4, 2012 at 10:24 pm:
Now you say:
So having questioned whether back radiation can be generated by absorbing gases, and my having answered it, you now point out that this is diverting the subject “off topic”.
Well done.
Congratulations on not interacting with any evidence. Just ignore all comments with experimental evidence and pretend they don’t exist.
I have provided the measured spectrum from FT-IT instruments. These instruments point up at the sky and measure the radiation coming down from the atmosphere.
I refer you – and readers who have missed it – to my comment from January 11, 2012 at 10:55 am. Not much point repeating it.
I will revert back to ignoring your statements.
SoD,
I find many words but I don´t find an answer to my key question required in order to start to consider your presentation and conclusions concerning ospectra:
“Experimenal evidence on the intensity of the signal you refer to is missing. Is it microW, mW, W or kW per square meter?”
Since this answer is missing it is quite logical on your side now to state:
“I will revert back to ignoring your statements.”
This is clearly the only possibility to stick to the famous “fairy tail” of an “Atmospheric Greenhouse Effect said to be caused by “Backradiation” of absorbing gases,
Congratulation, Therewith You remain fully in line with your collegues in IPCC,
Your citation of my statements needs a little correction:
In my pointing to the fact that CO2 is emitting into the space angle of 360,degree,any physisist would realize without any difficulty that “back radiation” has to produce a signal at the altitude of emission of LW radiation.
There is now chance however, that this tiny effect could alter the mein direction of radiation flow into space following the deccrease of densityof absorbinggases wit increasing altitude. You did not adress this argument!
What the hell, look at Fig.1 here, which shows exactly what you claim has not been shown. Problem is your particular mole has been whacked so many times that patience runs thin. There is a cottage industry taking such spectra.
To SoD
SoD quotes:
“Here’s a clue – optical thickness is linearly proportional to the number of absorbing molecules, but emissivity = 1-e^τ (where τ = optical thickness).”.
Please regard the remark of Nick Stokes:
“To get IR emission you need a resonant frequency in the force fields linking atoms. Solids and liquids have complex interacting forces between molecules. Gases don’t. It comes down to the oscillations excited on discrete collisions. Symmetric diatomic molecules have only one mode, stretching, and its frequency is not in the IR range. They are too stiff. Polyatomic molecules have bending modes etc.”
Evidently the emissivity of each individual molecule of said gases within a vacuum is equal to zero. Only interaction with other molecules (absorbing or not absorbing) can cause emission.
Therefore your “clue” lacks a physics basis.
By the way, isn´t often “ignoring statements” the basis for ignorance?
Are you familiar with Avogadro’s number? We’re not talking about vacuum here. At 101325Pa and 273.15K (STP) there are 2.7E19 molecules per cubic centimeter. At a pressure of 1Pa there are still 2.7E14 molecules per cubic centimeter. Collisional activation is not a problem in the atmosphere. In fact it’s required for local thermodynamic equilibrium (LTE) and therefore Kirchhoff’s Law, to apply.
Your idea that the atmospheric emission is cause by liquid and solid aerosols is ludicrous. We have satellites that measure those aerosols (MODIS, e.g.) and over vast stretches of the ocean, the aerosol optical depth, when there are no clouds, is extremely low.
Since your mind is made up and you aren’t interested in actually learning something, but only want to pontificate about subjects you clearly don’t understand, I see no point in further conversation.
To DeWitt Payne,
Sorry, but unfortunately you missed the point.
First :SoD presented (what is really a funny “clue”):
“Here’s a clue – optical thickness is linearly proportional to the number of absorbing molecules, but emissivity = 1-e^τ (where τ = optical thickness).”
Keeping the absorptivity and the “optical thickness” constant, the emissivity is increasing if adding an increasing number of non absorbing molecules. Therefore this “clue” is better to be placed into science fiction. (In order to avoid questions: This happens because an increasing number of collissions will reduce the time span during which molecules max stax in an excited state,) molecules.)
Second: The interaction of liquid and solid matter with LW Radiation in the atmosphere is being ignored wirhin the construct used to claim that absorbing gases would cause an armospheric greenhous effect.
Evidently you are ignoring my remarks concerning the relation between quantity of water, particle size and its reulting total absorbing/emitting surface.interfering with LW radiation within the atmosphere.
May be you did not even realize yet that (using data presented by Kiehl&Tremberth) a coverage of 60% of the surface by clouds is being “backradiating” abut 20 % of solar radiation into space. (You could easily fimd the explanation for this well known phenomenon big fraction of the earths albed by loking into a book explaining geometrical optics.)
Therefore I would not dare to recommend selling neither your umbrella nor any raincoat.
DeWitt Payne, Correction
Sorry, but unfortunately you missed the point.
First :SoD presented (what is really a funny “clue”):
“Here’s a clue – optical thickness is linearly proportional to the number of absorbing molecules, but emissivity = 1-e^τ (where τ = optical thickness).”
Keeping the absorptivity and the “optical thickness” constant, the emissivity is increasing if adding an increasing number of non absorbing molecules. Therefore this “clue” is better to be placed into science fiction. (In order to avoid questions: This happens because an increasing number of collissions will reduce the time span during which molecules may keep its excited state,)
Second: The interaction of liquid and solid matter with LW Radiation in the atmosphere is being ignored wirhin the construct used to claim that absorbing gases would cause an armospheric greenhouse effect.
Evidently you are ignoring my remarks concerning the relation between quantity of water, particle size and its reulting total absorbing/emitting surface.interfering with LW radiation within the atmosphere.
May be you did not even realize yet that (using data presented by Kiehl&Tremberth) a coverage of 60% of the earths surface is “backradiating” about 20 % of solar radiation into space. (You could easily find the explanation for this well known phenomenon by loking into a book explaining geometrical optics.)
Therefore I would not dare to recommend you selling neither your umbrella nor any raincoat.
Eli Rabett
“Eli takes it you used the 10 cm cell? (water vapor continuum and absorption on rotational lines)
However, being late to the party, and having looked at G&T last night, Kramm’s claims depend on defining thermal radiation as not heat which, as they say is nonsense. For example from G&T
“Fig. 32. A machine which transfers heat from a low temperature reservoir (e.g., stratosphere) to a high temperature reservoir (e.g., atmosphere) without external work applied, cannot exist — even if it is radiatively coupled to an environment, to which it is radiatively balanced. A modern climate model is supposed to be such a variant of a perpetuum mobile of the second kind.”
Denying that a thermally sourced radiative exchange between two bodies is an exchange of heat, well, you got a Humpty Dumpty problem bucky”
“Heat” tranferred from “cold” to “hot” matter by LW radioation,does not change neither the enthalpy nor the temperature of absorbing “hot” matter. Its ability to supply work remains unchanged Thats all!. What´s the problem?
on January 27, 2012 at 12:18 am
Define heat and explain why it is different from other forms of energy.
Heat is energy in transit and always is directed spontaneously from a higher temperature body to a lower temperature body.
Take for example the two plates in your paper .
They both radiate to one another
They both exchange energy
But heat (in your case, net radiative flux) only goes from higher to lower temperature.
Heat has the capacity to do work (turn into another energy form) in the given situation between the source and temperature sink.
A thermodynamics chapter including the Carnot Cycle only makes sense if you use this definition of heat.
If for instance you think radiation is heat and say heat then moves from the lower temperature object to the higher temperature object you are ( perhaps inadvertently) contradicting the second law of thermodynamics.
Other energy forms can be interchanged readily with almost 100% efficiency and are governed by the first law.
Heat cannot be changed into other forms with the same ease.
As well as the first law it also has to comply with the second law.
The Carnot Cycle section will explain it in much more detail.
If the heat is “directed” what Maxwell’s demon is doing the “directing”. You quickly get into second law problems if you impose a direction. The two plates radiate in ALL directions and that has important implications that you have missed.
Now tell Eli how you are going to extract work with 100% efficiency from two finite plates at two different temperatures.
Eli Rabett says
“The two plates radiate in ALL directions and that has important implications that you have missed.
Now tell Eli how you are going to extract work with 100% efficiency from two finite plates at two different temperatures.”
You obviously did not look at the Carnot cycle as I suggested.
You still seem to be confused about the definitions of heat and EM radiation.
The efficiency of a Carnot Engine which is the most efficient way of transferring heat (between a source and a sink ) to another form (such as electrical) is given by the formula
Efficiency = 1 – Tc/Th
Tc = Temperature of sink
Th = Temperature of source
Ex.
If Th = 600K and Tc =300K the efficiency would be 50% so in fact you will never get 100% conversion of thermal energy into another form.
If you were a student in Professor Gerlichs class and you said that Heat can flow spontaneously from a cold to a hot object I would imagine he would ‘go ballistic’.
Eli Rabett
“What the hell, look at Fig.1 here, which shows exactly what you claim has not been shown. Problem is your particular mole has been whacked so many times that patience runs thin. There is a cottage industry taking such spectra.”
Why don´t you use the sprectrum of the radiaton arriving from the moon to establish youre room heating? – A spectrum does not contain any information on the intensity of the signal! – You may well continue to ignore such triviality! My patience is well trained from experience communicating with people.
Why don´t you answer my question? Is it micoW, mW, W or kW what has been backratiated incited measurement of spectrum in the Antartica?
You were pointed at a spectrum of the emission from the atmosphere as measured from the surface. The equipment used MEASURED the intensity of the emission in W per square meter per sterradian per wavenumber. There are many such measurements that have been made. This is EXACTLY what you claimed has not been done.
One can also look at the absorption through the atmosphere using the moon surface as an IR source. J. Notholt, R. Neuber, O. Schrems, T.v.Clarmann,
Stratospheric trace gas concentrations in the Arctic polar night derived by FTIR-spectroscopy with the moon as IR light source,
Geophys. Res. Letters, 20, 2059-2062, 1993.
u. Wolff,
It’s good to see some interest. Of course, you should be able to do an order of magnitude calculation yourself from the FT-IR measurement. Just a numerical integration.
Have a read of the article that referenced this graph, that I pointed you towards on January 5, 2012 at 3:09 am – The Amazing Case of “Back Radiation” – Part Two:
Walden, Warren and Murcray, Measurements of the downward longwave radiation spectrum over the Antarctic plateau and comparisons with a line-by-line radiative transfer model for clear skies, JGR (1998):
u. Wolf: By letting the conversation be turned towards the radiation coming down from the clear sky in Antarctica in winter, you are falling into a trap. This is one location on the planet that is easy to show agreement between theory and observation – low humidity (no water dimers) and no clouds. It is harder to get agreement almost everywhere else on the planet, although there is sensible agreement between theory and observation almost everywhere the skies are clear.
You were correct earlier to focus on “liquid and solid” in the atmosphere, by which I assume you mean clouds made of water droplets and ice. Clouds are heterogeneous and constantly changing. The optical properties of some clouds are well understood (thick clouds with liquid water tend to emit blackbody radiation in the IR) and some have been studied intently by observation (but probably aren’t well understood). However, the real problem lies in predicting where clouds will form and what there optical properties will be at that location. Marine boundary layer clouds are currently a particular problem. Climate models even disagree about the sign of cloud feedback. In Antarctica, the experimenters sent a radiosonde up to measure the temperature humidity profile of the atmosphere before calculating the theoretical spectrum. AOGCM’s don’t have this luxury; they must predict what will be there before they calculate OLR and DLR.
Frank,
A trap?
In fact, a test of basic physics principles.
Which is why this particular spectrum is so useful. Instead of people in the blue corner agreeing that they disagree with people in the red corner..
..we find out what approach someone has to the basic physics of radiative transfer in the atmosphere.
Surely the essence of the scientific method is finding a way to prove or disprove a theory by stripping out all of the complications that make it too difficult to prove. And then, having repeated the experimental work to demonstrate the truth of a falsifiable theory finally science accepts the theory and uses it as a basic building block for more complex theory.
This particular paper wasn’t written to draw “skeptics” attention away from the role of water vapor, liquid water and ice in the atmosphere and present some happy story that saves “skeptics” from realizing the complexity inherent in climate.
Why was this investigation done and the paper written?
But it does have an extra value for our purpose. Those claiming that atmospheric physicists are wrong in the basics of radiative transfer (like u. Wolff) have to explain why theory and experiment match so closely.
SoD,
lets assume on May 1, 1992 the air above 1 square meter of ground would have contained only 0,1 kg of ice in form of particles having a diamter around 0,01 mm and being mixed with the 10 000 kg of air. Such particles are invisible against the blue sky, (which was actually dark during the experiment you are referring to. – A big fraction of water vapour carried into the polar regions is freezing around other aerosols especially during winter time. Experimental evidence is being produced via snow fall also.)
The absorbing/emitting surface of such solid matter would be around 30 m^2. The “atmospheric window” would therefore be closed to nearly 100%.
Now let´s calculate a little assuming an emissivity of 0.99 for ice:
A downward radiation of 76 W/m^2 – as measured – would result, if the temperature of the emitting surface of ice would be around – 72 deg.C, 192 K.
The surface temperature of 207 K at the icy ground – as measured – would have to emit an upward radiation with an intensity of 103 W/m^2.
These facts are the reason for my question concerning the missing quantification of an influence of CO2 on these two energy fluxes.
By the way, discussion “ad personam” is not practice in science und to me not even proper “etiquette” in bloggs. (Only ignoring can create ignorance!).
The spectrum of ice is a blob. There are no sharp absorption/emission lines such as are seen in these spectra. If the emission were from ice particles the spectrum would have appeared as continua.
Further, blue is ~ 450 nm, while the IR emission spectra are between 5000 and 50,000 nm so the blue sky has nothing to do with the case.
Stop throwing nonsense against the wall in the vain hope that something will stick. You clearly do not know anything about what you are going on about and have only succeeded in making yourself look foolish.
Walden, et.al. is available on-line at http://www.atmos.washington.edu/~sgw/PAPERS/1998_Walden.pdf
The imbalance between downward radiation in the winter and upward radiation from the surface is balanced (mostly) by transfer from the atmosphere. For this to happen, the atmosphere must be warmer than the surface. That’s known as a temperature inversion and it extends to well above the surface over the Antarctic Plateau and over the Arctic sea ice in local winter. In Walden, et.al., the temperature of the atmosphere increases by 29C at an altitude of between 3.5 and 4 km above sea level before starting to decrease again. The altitude of the surface is 2.9 km. Most of the temperature increase is in the first 100m above the surface.
DeWitt Payne,
please realize:
1. The “imbalance” equals 28 W/m^2 in winter, 34 W/m^2 in spring and 70 W/m^2 in summer.
2. It is the permanent energy flux from equator to polar regions in parallel to the surface prenventing surface temperatures to drop down to 30 to 40 K in winter, when only the heatflux out of the interior of the planet would be available.
3. It is this horizontal energy flux creating an inversion between surface and Tropopause where matter is emitting LW radiation into space and back towards the crust with a surface doubling that of the crust.
Neither your ideas of what happens nor the article in the link give any quotation to what extent CO2 could contribute to the magnitude of upward and downward radiation fluxes between surface and Tropopause.
u. Wolff on January 27, 2012 at 1:39 pm:
I find irony and satire get me through the day. The blog rules permit it (I wrote them):
So when people arrive at the blog with the “I know stuff” attitude and “60 years of physics is wrong”, yet are unwilling to engage with why 60 years of physics thinks its right, then I confess I find myself unable to resist making fun of them.
You can think of it as a character flaw if you like. I agree that part is not science. But it helps me keep going with this blog. It’s the gasoline that I run on when no science is presented by readers.
Back onto science..
I have provided a spectrum, a flux, the location and made the outrageous claim that the radiative transfer equations correctly calculate the spectrum. All nicely demonstrated in a paper that you can read for yourself.
These are shown together in the graph that I keep producing. (There are 100′s of such graphs around).
- Why do you think they match?
- Why do you think there is a big peak around 600-700 cm-1?
On January 4, 2012 at 10:29 pm you said:
You have to prove that. You haven’t proven it. You haven’t even tried as far as I can tell. Instead, you wave your hands..
The emissivity of water and ice does not have a spectral peak around 600-700 cm-1. This constitutes evidence against your theory. Would you like to find out the emissivity of water and ice? Do you know what it looks like?
You can see the reflectance in Emissivity of the Ocean:
This is why I have starting making fun of your crazy claims. And someone who claims such knowledge and yet can’t even convert a graph of spectral intensity to flux (to within an order of magnitude)? It can’t be real.
Someone who claims so confidently that back radiation is being emitted from water and not CO2 when the spectral characteristics match CO2 but are totally different from water – are you having a laugh?
Feel free to ignore evidence presented and I will mostly ignore you and occasionally surface to mock your confident claims.
As already requested, if you care about science, if you are interested in science, start by explaining what is wrong with the radiative transfer equations (see Part Six – The Equations and why it is that the theory matches the evidence (as already shown in the Antarctic DLR spectrum).
Remember, 60 years of physics confirms the radiative transfer equations. Decades of research by thousands of researchers confirms the spectroscopy of absorption/emission lines of gases.
You are arguing against proven physics.
And to avoid a “back radiation” bias, it is important to understand that the real atmospheric greenhouse effect is caused by the reduction of outgoing longwave radiation (OLR).
A proof that back radiation can be “saturated” while increasing a “greenhouse” gas can still reduce OLR can be found in Understanding Atmospheric Radiation and the “Greenhouse” Effect – Part Four.
SoD confirmes:
“You can even be insulting in an amusing/satirical kind of way.”
I am goin to start trying this just with a starter on saturday morning, (More to follow later):
Once upon a time there have been living people – calling themselves scientists – claiming the earth to be flat even after sailors told them,that the flag on top of an approaching vessel would always be the first thing to be seen.
There are presently living people recognizing that a mass flow of air arriving from warm ocean areas provides an energy flow of 70 W/m^2 to polar ground, They are absolutely shure that it does not deliver 1 to 10 ppm of ice into that column of air also. Are they perhaps “snow blinded”?
.
Frank
“u. Wolff: By letting the conversation be turned towards the radiation coming down from the clear sky in Antarctica in winter, you are falling into a trap. This is one location on the planet that is easy to show agreement between theory and observation – low humidity (no water dimers) and no clouds. It is harder to get agreement almost everywhere else on the planet, although there is sensible agreement between theory and observation almost everywhere the skies are clear.”
Unfortunately it is not just me falling into this CO2 trap, being quite costly for many people.
These “favourable conditions” for mathematiícal speculation using unavoidably oversimplified models exist – if at all – only on about 5 % of the planets surface. Weatherforcast demonstrates the existing limitations daily.
The planet is just a little disturbance within the radiation field of the sun, the system being far too complex and even the correlation between enthalpy and temperature happens not to be unique.
U. Wolff wrote: “These “favourable conditions” for mathematiícal speculation using unavoidably oversimplified models exist – if at all – only on about 5 % of the planets surface. Weatherforcast demonstrates the existing limitations daily.”
We aren’t talking about mathematical speculation in Antarctica. We are talking about principles of physics and data about the interaction between radiation and the constituent gases of the atmosphere. This information was obtained from well-controlled, reproducible laboratory experiments. Such experiments are the foundation of science. SOD has shown you evidence that this science correctly predicts the spectrum of DLR and OLR coming from clear sky with a KNOWN temperature and humidity profile.
If “mathematical speculation” means AOGCM’s, they are an entirely different subject. Before an AOGCM can correctly predict the DLR and OLR coming from clear sky, the model needs to have correctly predicted the temperature and humidity of the atmosphere. To accomplish that, it must properly deal with clouds, convection, precipitation and other phenomena. To the extent that such models are “mathematical speculation”, they don’t fail because they do a poor job modeling the interactions between LWR and clear skies; they fail because about half of the sky is cloudy and poorly understood. When you were talking about the interaction of LWR with “liquid and solid” in the atmosphere, I assumed you were talking about clouds.
Stainforth (Nature (2005) 433, 403-406) randomly varied the parameters controlling clouds and precipitation in the Hadley GCM within the range of values established by laboratory experiments and produced hundreds of different realistic models with climate sensitivity for 2XCO2 ranging from less than 2 degK to greater than 11 degK.
http://climateprediction.net/science/pubs/nature_first_results.pdf
SoD wrote:
“Back onto science..
I have provided a spectrum, a flux, the location and made the outrageous claim that the radiative transfer equations correctly calculate the spectrum. All nicely demonstrated in a paper that you can read for yourself.
These are shown together in the graph that I keep producing. (There are 100′s of such graphs around).
- Why do you think they match?
- Why do you think there is a big peak around 600-700 cm-1?
On January 4, 2012 at 10:29 pm you said:
Back radiation – as observed – is being emitted from water, ice or other aerosols exclusively.
You have to prove that. You haven’t proven it. You haven’t even tried as far as I can tell. Instead, you wave your hands.”.
My claim goes a lttle further than concerning “backradiation” or “LW radiation reaching the earths crust” only, what ever you prefer:
“Liquid and solid matter within the atmosphere are creating the phenomenon whichn is called “amosheric greenhoouse effect”.
:
Here a repitition of whatever “proof” can be presented:
The specific emissivity of water or ice surfaces is identical for such matter if located at the surface of the crust or in form of particles of different size wihtin the atmosphere.
The latter is emitting LW radiation towards space and crust with an intensity dependent on its temperure. It is recieving energy fluxes from the crust in form of heat of´condensation/sublimation, convection, conduction and via absorption of LW radiation.
Whenever the projection of such matter in the atmosphere covers a spherical surface completely, the atmospheric window for LW radiation is being.closed,
Experimenal proof for the existance of such state would have to generate data on quantities, sizes and spatial distribution as a function of time for the total globe. That is impossible. (Realize that individual and especially thinly distributed and or small particals of water are not or not easily visible.)
However, as pointed out already, precipitation, coverage and lifetime of visible clouds, growth time of particals, relation between quantity, particel size and acting surface make it highly probale, that any remaining open window must be very small.
As a consequence of this situation, the differences between the time dependent local temperatures distributions in matter within the atmosphere and at the crusts surface are defining the atmospheric greenhouse effect” as being observed.
Any interaction of CO2, water vapor and other absorbing gases would not alter temperatures to any detectable extent.
Remain famous Spectra at points in time at even untypical locations:
You “have provided a spectrum, a flux, the location and made the outrageous claim that the radiative transfer equations correctly calculate the spectrum.”
I never expressed any doubt that the “transfer equations (havibg used it quite often) can correctly calculate the spectrum” if data are available (the topic of this post). However the atmospheric greenhouse effect is produced by energy fluxes not by sectra.
Therefore It is exclusively your obligation to show and to give proof on what effect absorbing gases would create in 95 % of the real world on our water planet earth.
Using your words, the simple “hand waving” statement that the above calculation agrees with some measurement does not do the job .
SOD replied to my comments about a trap:
“A trap? In fact, a test of basic physics principles.”
Commenter Wolff was complaining about ignoring “interaction between LWR and liquid and solid in the atmosphere” (clouds with water droplets or ice, I presume). To some extent, he’s right: About half of the sky is cloudy and the simple physics of homogeneous gases is replaced with something far more complicated. I did a quick search to see what you have written about cloud feedback and the physics of clouds. I found a four-part series on water vapor and clouds, but it’s mostly about water vapor, not clouds. (Perhaps I missed some other posts.) Your Antarctic spectrum switched his focus from clouds – a subject where there is significant uncertainty and I’d like to learn more – to clear skies in Antarctica – the simplest LWR-atmosphere interaction on the planet. Understanding clear skies in the Antarctic can tell us that there is some AGW in GW. More than any other topic, however, clouds are likely to tell us whether AGW will turn out to be CAGW. For scientists, the only
Of course, the clear Antarctic sky is a test of basic physical principles. It may be difficult to have a sensible discussion about clouds with anyone who won’t acknowledge that basic physics works well for the simplest location on the atmosphere.
SoD,
“Back to science”.
Concluding in an “amusing kind of way” – the “chain of proof” in favour of an “Atmospherig greenhouse effect caused by absorbing gases” makes me remember the following story:
Once upon a time Indians had been asking their Chief:
“What is the next winter going to look like?” —
Being a politicial scientist he responded spontaneously: –
“”It´s going to be very, very cold!”
Immidiately they started collecting wood. – However, Observing them working he felt a ittle inconvenient and went into the big city in order to consult with the famous “Atmospheric Scientist”:
“What is the next winter going to look like?” — The delighting answer:
“”It´s going to be very, very cold!” —
“By the way, would you mind to tell me know why this is goinbg to happen?” -
“The Indians are collecting wood like hell!”
Frank,
u. Wolff’s “complaint” was that CO2 has no impact on “back radiation” and that water and ice are the entire cause of “back radiation”.
In fact, the original complaint was: “Therefore no “back radiation” could be generated by absorbing/emitting gases.“.
A strong claim which is easily falsified.
You are correct and have missed nothing. I have written almost nothing about clouds.
This is exactly my point. This was the reason for raising the Antarctic spectrum. It is a test, not a trap.
SOD: After seeing how this conversation has evolved, I regret jumping inwithout fully understanding what had been said earlier. Wolff (apparently accidentally) reminded me that complete knowledge of the clear sky has little utility unless combined with a decent understanding of the cloudy sky. Perhaps some day you’ll tackle this subject.
Frank,
Everyone is free to chose the location to study basic physics. Antarticwa is perhaps not the most convenient place:
CO2 is emitting LW radiation having a known spectrum, the gas concentration has its maximum close to the surface. Therefore at any place around the globe one can pick up this signal. You will find this remark in my comments here.
Discussing liquid and solid matter must not be limited to clouds. Clouds become visible only, when the particle size and density of such matter starts contributing to the albedo. (60 of cloud coverage reflects 20 % of solar radiation only but is intransparent for LW radiation).
The surface of each particle of ice and droplet of water is continuously absorbing and emittig LW radiation.
Liquid and solid matter in the atmosphere present in blue skies even over locations at high elevation in desert areas is one reason for putting Hubble into space. 1 kg of water in form of particles of 0,01 mm diameter have a surface area of 300 m^2.
SoD,
“u. Wolff’s “complaint” was that CO2 has no impact on “back radiation” and that water and ice are the entire cause of “back radiation”.
In fact, the original complaint was: “Therefore no “back radiation” could be generated by absorbing/emitting gases.“.
A strong claim which is easily falsified.”
I have been and I am adressing energy fluxes influencing signifcantly or at least detectably tempertures of matter in crust and atmosphere.
Therefore I have to continue to defend both statements:
Whereever a coverage with liqid or solid matter exists, the energy flux of back radiation is being generted from that emission of LW radiation. Any variation of interactions with absorbing gases cannot have an influence on the magnitude of that flux.
According to my observations and estimates this situation holds at least for about 95 % of the crusts surface where “back radiation generated by absorbing gases does not influence downward energy flux.
Before you could falsify this “complaint” you would have to start investigating the occurance, shape and distribution of such solid and liquid matter but not in visible clouds onlly!!
Concerning the rest of 5% of polar regions and deserts you should perhaps consider at least, that
1. its contribution to energy fluxes influencing the enthalpy of the system is rather small and
2. in an attempt to calculate the magnirudes of outgoing and backradiated energy fluxes the vertical distribution of densities of absorbing gases must not be neglected forreasons exlained elsewhere in this post.
Wolff, if what you say has any validity please explain the sharp spectral structure in the OBSERVED emission spectra. Hint: liquids and solids such as you describe do not have such sharp lines.
To Eli Rabett,
as I pointed out elswhere in this post this peek you refer to is a signal stemming from emission of CO2.
Its impact on “backradiation” to the crust of the earth I explained in my response to SoD on January 29, 2012 at 12:51 pm.
Concerning your demand to “Define heat and explain why it is different from other forms of energy” you may read the explanation Bryan has provided kindly.
Come back with further questions If nescessary.
[...] also produced by Kramm & Dlugi, who think the greenhouse effect is some unproven [...]
Frank, SoD
“SOD: After seeing how this conversation has evolved, I regret jumping inwithout fully understanding what had been said earlier. Wolff (apparently accidentally) reminded me that complete knowledge of the clear sky has little utility unless combined with a decent understanding of the cloudy sky. Perhaps some day you’ll tackle this subject.”
That is a great idea to be distributed and forwarded to IPCC also quickly !!!
When I made a part time side step into the fairy tails concernimg CO2 and tempertures five years ago trying to understand clouds had been the initiator. (“Accidentily” I did understand commercial condensers and fog chambers fairly well already)
SoD,
““Blah blah blah” vs Equations…… also produced by Kramm & Dlugi, who think the greenhouse effect is some unproven [...]”
energy flux into earth = solar energy fluy – reflected fraction
erngy balance of earth = energy flux into earth – outgoing ffux into space
earths enthalpy = Integral of enerngy balance over time.
Uncfortunately Important data required to solve these equations are hidden in clouds thus making respective mathematical models to “comforters” not giving any milk in “proving that absorbing gases are creating an atmospheric greenhouse effect.
Are not Kramm & Dlugy adressing just this case of the missing data even without entering into resulting limitations of models?
You and Bryan are missing a lot. If the heat is “directed” from a hotter to a lower temperature plate what Maxwell’s demon is doing the “directing”. You quickly get into second law problems if you impose a direction. The two plates radiate in ALL directions and that has important implications that you have both missed.
Now tell Eli how you are going to extract work with 100% efficiency from two plates at two different temperatures radiating thermal energy. (Hint: Solar cells require a cold heat bath, which, as the sun radiation field is effectively 6000K, is not too hard to find, but is still needed)
[...] also produced by Kramm & Dlugi, who think the greenhouse effect is some unproven [...]
To Eli Rabett,
I used Uranium for theses plates, put them into plain water and let the steam drive a turbine, using the antarctic winter as the cold end! The efficiency of this machine had been quite high even with CO2 backradiating!
It is still limited by the second law because you have constructed half a steam engine.
Eli Rabett,
Didn´t you know that 5000 years have passed already with an atmospheric steam engine driving vessels upstream in Egypt?