Geomagntic - Climate, page-99

They aren't absorbing infrared light, no. There are several methods of heat transfer. Simplistically, radiation, is the direct transfer of infrared light, then there is conduction, whereby heat (energy) flows to adjacent matter in order that it be equally distributed. Thirdly there is convection, due to movement of matter through bouyancy.

For Infrared radiation, different materials will absorb it, and other materials will reflect it, and still others will let it pass through. A leaf is green for example, because it absorbs all spectral colours, but green light bounces off it into our eyes. A pane of glass maybe clear, as light passes through it without being absorbed, but it may still get hot in the sun by absorbing non-visible wavelengths.

This brings us to conduction, which can be thought of simplistically as particles imparting their energy to other particles by kinetic action. Imagine a room full of soccer balls at rest. This is cold. Now imagine the soccer balls are all bouncing around the room and bouncing into each other. This is heat energy.

Let's say a water molecule, the most abundant greenhouse gas in our atmosphere averaging 26 times higher than CO2 and which absorbs a much broader spectrum of energy, absorbs a photon of IR radiation. It does this by jumping its electrons to a different state, which makes it jiggle about in a slightly different manner due to the forces between the electrons and protons within the atom. As a result of this jiggle, the water molecule bumps against an O2 or N2 molecule, which bumps against another and another etc. This is our conduction heat.

Let's say this area of more energetic (hotter) O2 or N2 is busily knocking other molecules around. The density of molecules in that area decreases, because everything is moving around, the region of hot air expands. Since there is now less mass per given volume, the lighter area of warm air, is pushed upwards through bouyancy, as colder denser air tries to push in from the bottom. The hot air rising, is the third mechanism of heat transfer, convection.

Overly simplified. of course.