In Atmospheric Circulation – Part One we saw the Hadley circulation: convection in the tropics and subsidence in the subtropics: Figure 1 The distribution of relative humidity in the atmosphere is a result of this circulation. The sun heats the tropical ocean surface which both warms the air just above it and also evaporates water into this air. This hot … Continue reading Clouds & Water Vapor – Part Five – Back of the envelope calcs from Pierrehumbert