Michel wrote: What I’m confused at is the 15 micron photon is -80C. I thought energy had no temperature? Is there such a thing as an “emitting temperature”?

Planck’s Law says that a blackbody at a given temperature will emit radiation a wide range of wavelengths – a spectrum. That spectrum always has a similar shape, but the wavelength where the maximum intensity radiation is emitted varies inversely with temperature according to Wien’s Law (which can be derived from Planck’s Law). Emission at all wavelengths increases with temperature. And the total energy emitted by a blackbody at all wavelengths increases with the fourth power of temperature according to the Stefan-Boltzmann equation.

Consider the parabola y = -x^2 + bx + c. If you are given a single point on this parabola, you can not deduct what coefficients (b and c) were used to create this parabola. You need to be provided the coordinates of at least two points (and many more if you aren’t sure the points come from a parabola.) However, from taking the derivative, you do know that the maximum on the parabola will be found at b/2. Planck’s Law behaves similarly: Given a single photon of 15 um radiation, you can’t say anything about the temperature of the object that emitted it.

Notice that I said emission from “blackbodies” follows certain laws. Not all materials behave like “blackbodies”. “Graybodies” emit a spectrum similar to blackbodies, but less at all wavelengths. We say their emissivity is less than 1. Other materials – most famously the atmosphere itself – don’t emit like blackbodies or graybodies. If you could record the spectrum of the thermal radiation shining down from the atmosphere at night, you would clearly see that the spectrum doesn’t resemble the spectrum of a black- or graybody. You can simulate that spectrum online using the Modtran link provided by DeWitt.

When Planck derived his law, he assumed that molecular collisions produced a Boltzmann distribution of energy among ground and excited states. Emission of a photon of a particular wavelength (E = hv) was associated with a molecule in an excited state returning to a lower energy state with a difference in energy of E. A Boltzmann distribution has a factor of exp(-E/kT) that describes the decreasing likelihood of a molecule being in a high energy state. Therefore a blackbody at a given temperature emits a range of wavelengths. Planck also assumed that blackbody radiation was in equilibrium with the molecules through which it was traveling. (Equilibrium means the number of photons being emitted is equal to the number of photons being absorbed.) However, we know that simple molecules like the GHGs in the atmosphere absorb and emit very different amounts of radiation at different wavelengths of thermal infrared – more than ten orders of magnitude different per molecule. The assumption that radiation traveling through the atmosphere has a blackbody intensity appropriate for the local temperature (or any particular temperature) breaks down in the atmosphere because there aren’t enough photons being absorbed and emitted to produce equilibrium. Therefore, in the atmosphere, radiation and the energy it conveys are calculated using a different law: Schwarzschild’s equation for radiation transfer.

Gas molecules in the lower atmosphere collide and change their kinetic energy about 10^9 times per second, and some collisions create or “relax” excited internal vibrational and rotational energy states. (99.9+% of excited states are produced by collisions rather than absorption of a photon.) If the temperature of a molecule were proportional to its kinetic energy, it would be changing radically 10^9 times a second. Instead, temperature is defined as being proportional to the MEAN kinetic energy of a large local group of colliding molecules. 10^9 individual collisions per second per molecule between members of the group don’t change the temperature of the group. Individual molecules don’t have a meaningful temperature. The kinetic energy (or internal vibrational or rotational energy) possessed by any one molecule isn’t determined by the local temperature. Photons carry energy between two molecules without regard to the temperature of the local groups to which they belong, but the NET FLUX of radiative energy obeys the 2LoT. Many technically competent skeptics understand nothing about why the behavior we observe in the macroscopic world – the laws of thermodynamics, Planck’s Law, PdV work, PV = nRT, etc. – is a result of individual molecules and photons obeying the laws of quantum mechanics. Some are motivated to spread fantasies about this subject proving the fundamental physics used by conventional climate science is deeply flawed.

Climate models (AOGCMs) are deeply flawed, but all models based on parameters have flaws. The question is whether such models are useful.

]]>Michel,

An individual photon doesn’t have a temperature. It only has an energy. An individual photon carries no information about its source of emission. There is no difference between a 15 micrometer photon emitted from the surface of the sun or from a blackbody at -80C. Temperature is a collective property of a large number of particles. The photon ‘gas’ inside a cavity has a temperature. It’s the temperature of the cavity wall. Even talking about the temperature of an individual photon is unphysical. This is the problem with trying to explain physics without using mathematics. It’s easy to form sentences that look like they make sense, but are actually nonsense.

]]>What im confused at is the 15 micron photon is -80C. I thought energy had no temperature? Is there such a thing as an “emitting temperature”?

]]>Michel,

The owner of the blog you reference is obviously ignorant of physics. Wein’s law only applies to black or gray bodies and then only for emission if the emissivity of the body is constant, which is not true of the atmosphere. Again, the brightness temperature of the source has absolutely nothing to do with absorption by the target. You can’t single out an individual or even small range of wavelength and assign it a temperature. Even a source as bright and hot as the sun emits radiation at 15 micrometers, just not very much compared to the radiation intensity in the visible. But the emission intensity at 15 micrometers at the sun’s surface is still orders of magnitude more than for a blackbody source with a peak emission at 15 micrometers and a temperature of 193K.

The important number is not the peak emission wavelength, but the total energy under the spectral curve, which can be assigned an effective temperature using the Stefan-Boltzman equation (see: https://scienceofdoom.com/2010/10/24/planck-stefan-boltzmann-kirchhoff-and-lte/#comment-117206 for example) and the difference between the total energy emitted by and absorbed by the surface. If you want to play with atmospheric spectra, go here: http://climatemodels.uchicago.edu/modtran/

]]>On the HOKEYSHTICK blog, the link he provides is a google driver and he’s put an entire chemistry book online (not sure how legal that is), but he also shows the picture of the pages in the blog post. 146 is correct. I verified it. Can anyone look at the source and find out whats wrong? Im no expert.

]]>So i found what his source is from his constant repetition of these points.

“Since the emitting temperature of ~15um photons from atmospheric CO2 is -80C by Wein’s & Planck’s Laws (also explained in the reference below), these photons cannot possibly be thermalized/increase the energy or temperature of the much warmer Earth surface at +15C.”

This is from http://hockeyschtick.blogspot.com/2015/08/plancks-quantum-theory-explains-why-low.html

Im not into the specifics of this, but can you explian why this is wrong?

]]>Minor etiquette note, we don’t use the d..er or d..ist words here. Kind of pejorative.

]]>Yeah so his last comment is probably the “last word” before he stops posting. He basically said i was wrong and then posted a link

https://www.youtube.com/channel/UCDK7p7ivYprBgjDNvYwmk5Q

Climate of Sophistry. A likely “denialist” source of misinformation.

So it seems you are right. I pushed him and he offered nothing.

]]>Michel wrote: “So even if we have certain formulas he is playing on the “well we dont know that this is exactly what’s happening” argument.”

This statement is completely incorrect. We have a theory – quantum electrodynamics (QED or quantum mechanics) – that describes exactly how molecules and photons interact. That theory has been thoroughly tested and confirmed over nearly a century and the key measurements on the most important GHGs were made long before climate change became an issue.

In the case of radiation and atmospheric GHGs, QED starts with Einstein coefficients, the probability that a single molecule will absorb or emit a photon of a particular wavelength. And with the Boltzmann distribution of energy that determines the temperature-dependent probability that molecular collisions will create and excited state capable of emitting a photon. On a macroscopic scale, those probabilities become the absorption and emission cross-sections used in Schwarzschild’s equation for radiation transfer, some variant of which is what climate scientists use when calculating what they obscurely refer to as “radiation transfer”, those fluxes you see on diagrams that appear to violate the 2LoT — until you understand that the 2LoT is referring to the heat – the net flux of energy. (In addition to absorption and emission, scatteing is also important under some circumstances at some wavelengths, but it is not important for GHGs and thermal infrared radiation. Scattering of visible light is what makes the sky appear blue.)

To make matters much more obscure, the Schwarzschild’s equation simplifies to Planck’s Law and the S-B equation when radiation is in thermodynamic equilibrium with matter (and absorption and emission rates are equal). Such an equilibrium does not exist at all wavelengths and altitudes in the atmosphere, and the GHE and radiative forcing arise for exactly this reason. Elsewhere, these laws work pretty well. Such an equilibrium was first studied using hot black cavities, and the radiation they produced is called blackbody radiation. These equations contain none of the terms that are critical to radiation transfer in the atmosphere: the amount of GHG, the wavelength-dependent absorption cross-section, and the dependence on the distance radiation travels. The S-B law, which is all many really learn about (W = eoT^4 has a constant, o, derived from other fundamental constants, temperature and a fudge factor, emissivity. The subtleties that produce radiative forcing in our atmosphere have vanished.

Our host and others like to point out skeptics’s inability to express their objections in terms of the equations of accepted physics. Alarmists – I don’t include anyone here in that group – want the public to think that GHG-mediated warming is a simple subject that anyone can understand. Therefore, I personally found the path to enlightenment full of bobby-traps like the 2LoT until I was shown Schwarzschild’s equation. However, this is differential equation that is difficult to understand and work with. (Likewise, the 1s, 2s, 2p, etc. orbitals for an electron in a hydrogen atom, which are the fundamental building blocks of chemistry, are the solutions to another fundamental differential equation, Schroedinger’s equation. Most may need to reach graduate school in chemistry or physics before learning about that subject.) For me personally, Schwarzschild’s equation is the Rosetta Stone that links quantum mechanics (Einstein coefficients), absorption spectroscopy that many learn about in basic chemistry, what happens when absorption is “saturated”, blackbody radiation in basic physics, and radiative forcing in the atmosphere. Few endorse this position, but I wrote an article for Wikipedia for those capable of benefitting from it.

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