The Knowledge of Photons: We often see the statement from climate lukewarmers and alarmists that the radiation from a cool object (such as the atmosphere) can not “know” that it is not supposed to travel to and heat up a warmer object (such as the surface), and thus, radiation from a colder object will heat up a warmer object. That is, the colder atmosphere must heat the warmer surface. 
Of course, this defies all common sense and heat transfer mathematics and thermodynamics, but alas, it is what they say. They use this “net flow” argument, where cold heats up hot and hot heats up cold, but the “net heating” is hot heating cold since the hotter heats the colder by a larger amount.
But simply look at the logic: if cold heats hot, then as hot heats cold, the colder will heat up the hotter more, thus heating the colder more, thus heating the hotter more…ad infinitum. So, it’s ridiculous. And of course, heat does not flow from cold to hot in any case, and heat flow input is what is required for temperature increase.
Look at the 1st Law of Thermodynamics:
First law of thermodynamics: When energy passes, as work, as heat, or with matter, into or out from a system, its internal energy changes in accord with the law of conservation of energy. Equivalently, perpetual motion machines of the first kind are impossible.
So, internal energy in the thermal case would be thermal energy measurable as the system’s temperature. To increase temperature when the action of work or exchange of matter are not occurring, then one requires heat. Thus for the electromagnetic case, look at the radiative heat flow equation (for 2 parallel walls with unit emissivity say):
Q’ = A*σ*(Thot4 – Tcool4)
This defines Q’ as the heat. There is a hot and cool term, and there is an exchange of energy between them since they are subtracting from one to the other; however, only that result after subtraction is heat. Only Q’ is heat. The radiation from the cool object to the hot object is not heat, and only the greater portion of the radiation from the hot object relative to the cool object is heat, and it transfers or flows only in the direction from the hot object to the cool object, from the greater power to the lesser power.
Since these are very basic laws of thermodynamics and heat transfer, then it has been totally established that a cool object doesn’t make a warmer object warmer still. And hence the radiative greenhouse effect of climate alarm, and climate alarm which depends upon it, is false. And we didn’t have to look at any pretty pictures to get here…simply math and logic. If you want a different result than that, then you’re going to have to change the 1st Law of Thermodynamics. Good luck with that.