) what Im saying is not that an atmospheres IR-absorbing/emitting properties dont count for anything. What Im saying is simply that the atmospheres DEGREE of IR activity (that is, its concentration of IR-active constituents) doesnt matter. Either the atmosphere is IR active, or its not. There is no in between. No gradation. Because as soon as its become IR active, atmospheric circulation (convection) takes care of the rest. When it comes to atmospheric MASS, however, it DOES matter whether its large, intermediate or small. And the real-world evidence for this is: Mars >> Earth/Titan >> Venus