I submitted my simple explanation as to why Earth's average surface temperature is what it is* over on hard-core pseudo-scientific Alarmist website Science of Doom.
* A planet will settle at a temperature so that it is emitting as much LW radiation to space as it gets in SW radiation from its sun. On earth, only the cloud tops and the cloud free sea/land surface can emit directly to space. Cloud tops and sea/land HAVE TO settle at the temperatures they are.
There is a separate closed cycle that operates between clouds and the sea/land below them, which can be ignored when we look at LW going to space (yellow box in my third diagram in the first link).
However this closed cycle works (it's heinously complicated), it will always be overridden by the fact that the temperature difference between sea/land and cloud tops is dictated by the lapse rate, which in turn is dictated by gravity; the specific heat capacity of the atmosphere; and the impact of the latent heat of evaporation (plus/minus a few other bits, like geo-thermal or electrical energy).
Imagine the lapse rate like the surface of a still reservoir. The water surface will be level. If you pump water from one end to another, it will not change the 'flatness'; the water will just sink back in the opposite direction to being level again. Similarly, the atmosphere can 'pump' as much radiation energy down as it likes (cooling things higher up and warming the sea/land); an equal and opposite amount of energy will flow back up again to reinstate the fixed and known lapse rate (cooling the sea/land and warming things higher up).
Maybe the sea/land warms up the air above it by conduction/convection, which in turn warms the air above that, all the way up? Maybe there's more evaporation from the sea/land? Maybe the sea/land just reflect the radiation back up? Overall effect as measured by thermometers = net nothing.
And surely, it is only absolute temperatures that we care about, not the precise mechanism of how it happens?
The comments and replies are difficult to follow because of nesting of replies-to-replies and because they simply deleted some of my replies. They started off by just calling me a Climate Denier etc, but one commenter, Frank, humoured me. His latest response was this:
Mark: There are two energy balances you need to deal with: the energy balance across the TOA and the energy balance at the surface. The [Kiehl and Trembert] energy budget has both. The existence of DLR is only important to the surface energy balance. You can only “prove” DLR doesn’t exist or transfer heat to the surface by studying the energy balance AT THE SURFACE.
I never said that there wasn't any downwards longwave radiation. I just said that you can ignore it when estimating likely temperatures - see my level reservoir example.
Energy balance across the TOA is the simplest because you only need to deal with radiation, which in principle can be calculated given the known temperature and composition of the atmosphere.
This seems to be his tacit admission that my simple calculation is in fact correct.
Calculating the energy balance at the surface is more complicated, because you need to add convection of latent and simple heat and DLR to the energy fluxes arriving at the surface. You completely ignore latent and sensible heat, and therefore CAN’T DRAW ANY CONCLUSIONS ABOUT DLR!
'Energy balance' is in fact very easy because you don't need to worry about what type of energy it is. You can work out from sea/land upwards, layer by layer, how much total energy each layer has - mainly thermal energy (warmth), with significant amounts of potential energy (gravitational energy - which goes up with increasing altitude/falling temperature) and latent heat (which is highest immediately above the oceans and tails off as you go up when gaseous water vapour releases that energy again by condensing).
And you find that the total energy at all altitudes in the troposphere is exactly the same, which is what you'd expect, it's like entropy. Radiation is just one of many mechanisms that works towards that balance, making sure that the lapse rate is maintained, radiation energy itself is not conserved or stored and does not show up in the overall balance (don't confuse stocks with flows!).
(NB This energy balance does not hold in the stratosphere, where the sunshine warms things from above when ozone absorbs it (converts it to thermal energy), so total energy goes up with increasing altitude - up to the point where the air is too thin and there is no measurable ozone. The same as oceans, which are warmed by sunlight from the top down. Water is not a gas, so there is no lapse rate. Again, red herrings.)
So... he believes in some magically self-reinforcing one-way energy transfer system and ignores all the other effects that cancel it all out again. it's like believing in the sloping water surface on a reservoir -and that once you have got a slope, it will become ever steeper of its own accord. Sorry, not good enough and it's obviously nonsense. It's an answer desperately looking for a question.
Onwards, ever onwards!