The above plots of temperature vs pressure in planetary atmospheres indicate that the surface temperature of a planet with an atmosphere is determined by its blackbody temperature, as the temperature of the atmosphere at a pressure of about 0.3 bar attained at a certain altitude and then moderated by a certain lapse rate (less than g/c_p where g is the gravitational acceleration and c_p the specific heat of the atmosphere at constant pressure) to set the surface temperature. The blackbody temperature would then be the minimum temperature of the atmosphere attained at a pressure of about 0.3 bar, and the planet surface temperature would be independent of the composition of the atmosphere, as long as the lapse rate would not be subject to change.
The greenhouse effect, supposedly influencing the temperature of the Earth surface, as an effect depending on the radiative properties of the atmosphere, would thus be zero. In particular, with a given lapse rate the Earth surface temperature would be independent of the amount of CO2 in the atmosphere.
The rationale would be that a gas at a pressure of more than 0.3 bar radiates like a blackbody. Is this true?
Academics, I have found, are one and all confused about "blackbodies", to such an extent that just a competent, independent physicist (not climate scientist) like myself knows enough more than they (you) do to be competent -- there are no competent climate scientists, in my professional (but heretical, according to consensus scientists) estimation.
SvaraRaderaOne can gain insight by using the Standard Atmosphere model of the Earth's troposphere, whose validity I precisely confirmed when I compared the temperatures in that range of pressures to the temperatures in the Venus atmosphere at the same pressure points (see my "Venus: No Greenhouse Effect", which is the definitive disproof of the greenhouse effect, along with several other fundamental mistaken beliefs in the consensus theory, including that the atmosphere is warmed by absorption of incident solar radiation, not by heat from the warmed planetary surface as scientists almost universally believe). Then one can see your hypothesis above is not correct, for several reasons:
1) The 100 mb level in Earth's atmosphere is above the troposphere, thus outside the range of the tropospheric lapse rate structure. The top of Earth's troposphere, in the Standard Atmosphere, is about 226 mb pressure (or roughly 200 mb, not 100 mb).
2) I aver there is no such thing as "radiating like a blackbody", without specifying the other forms of heat transport from the body. A body, black or otherwise, will radiate at whatever rate is necessary so that, in combination with the convection and conduction of heat from the body, total outgoing power equals incident power at constant temperature. A blackbody will only radiate as much power as it absorbs, at constant temperature, if it is surrounded by vacuum and can only lose heat through radiation. That should be obvious to physicists working in the field, since otherwise any additional energy lost through convection and conduction would not be balanced (i.e., only the incident and outgoing radiational powers being considered balanced).
3) If by "blackbody temperature" you mean the solution of the equation
S( 1 - α )/4 = σ T^4, S=incident solar intensity
then even at 226 mb -- the actual top of Earth's tropospheric lapse rate structure -- the temperature is not the blackbody temperature of the Earth (with α = 0.3). Your hypothesis doesn't work, both because you consider the wrong pressure level as "top of the lapse rate", and because, despite what climate scientists believe, NO level within the atmosphere, within or even above the troposphere, emits strict blackbody radiation (nor CAN it so emit, from elementary physical considerations of the existence of convection and conduction within the atmosphere--so the radiative transfer theory as used by climate scientists is wrong).
I outlined what I believe is the proper use of the Stefan-Boltzmann blackbody equation here, where I emphasize that the key is the radiational power ABSORBED (if a blackbody and non-blackbody, in a vacuum, both absorb the same power, they will necessarily attain the same temperature).
I firmly believe climate science WILL NOT ADVANCE, unless and until my Venus/Earth analysis is properly confronted and accepted, by the scientific community, as the definitve evidence for correcting climate science. No one can identify what errors still need to be corrected, including my own if there are any, until they understand the fundamental correctness of my Venus/Earth analysis, and its critical importance.
I see your points and agree with your Venus analysis showing no greenhouse gas effect.
SvaraRadera