I would like to congratulate Roy Spencer for yet another excellent and accurate account of the greenhouse effect. A good read for all those greenhouse effect deniers out there who more or less deliberately obscure matters so that ordinary people cannot think clearly. Spencer writes
"One of the first things you discover when putting numbers to the problem is the overriding importance of infrared radiative absorption and emission to explaining the atmospheric temperature profile. These IR flows would not occur without the presence of “greenhouse gases”, which simply means gases which absorb and emit IR radiation. Without those gases, there would be no way for the atmosphere to cool to outer space in the presence of continuous convective heat transport from the surface.
Indeed, it is the “greenhouse effect” which destabilizes the atmosphere, leading to convective overturning. Without it, there would not be weather as we know it. The net effect of greenhouse gases is to warm the lowest layers, and to cool the upper layers. The greenhouse effect thus continuously “tries” to produce a lapse rate much steeper than the adiabatic lapse rate, but convective overturning occurs before that can happen, cooling the lower troposphere and warming the upper troposphere through a net convective transport of heat from lower layers to upper layers."
Now for some comments. The convective overturning results in a bouyant layer of air characterized by a constant potential temperature, which, as far as I know, is not identical to the "adiabatic lapse rate". This could be a source of confusion, and it is of utmost importance for everyone to clearly understand how the convective "lapse rate" of Roy Spencer differs from for example that of H. Jelbring and others. For Roy Spencer it is the MAXIMUM lapse rate that a convective layer can TOLERATE. Greenhouse gases would like to steepen it further though. For H. Jelbring the dry adiabatic lapse rate is the lapse rate that an air parcel MOST HAPPILY installs itself into, because that is its most relaxed state.
Put in more technical terms, they differ through their interpretation of the thermodynamic system as either beeing very far from equilibrium, or rather close to equilibrium. In previous post though, I have tried to expose how the greenhouse hypothesis is very ambiguous indeed on whether it is in equilibrium or out of equilibrium. But that is another story that I will leave for now. I would though like to propose some intermediate solution:
Could it be that it is the sunlight, and not the greenhouse gases that destabilizes the atmosphere. It is so simple that it sounds almost silly.
Moreover, could Spencer or someone else come up with BOTTOM-UP description of how the greenhouse gases actually destabilize the atmosphere. I tried to construct my own radiative transfer model in the posts "A simple radiation model", "The heat equation revisited", which were initially critisized for not taking into account a variable thickness of the atmosphere, which I did in, "It's the density, stupid". The latter did not alter my previous conclusions, but as far as I can see strengthened them.
But finally, I think we should accept Spencers challenge and try to put numbers into our models. I will be busy with other things for a while, but maybe there is some young talent out there who can perform it, who knows.