C02 is responsible for absorbing infrared radiation, as both nitrogen N2 and oxygen O2 don’t absorb it.
“Not all gas molecules are able to absorb IR radiation. For example, nitrogen (N2) and oxygen (O2), which make up more than 90% of Earth’s atmosphere, do not absorb infrared photons. CO2 molecules can vibrate in ways that simpler nitrogen and oxygen molecules cannot, which allows CO2 molecules to capture the IR photons.”
Which means that the “heating of air” by infrared radiation (which is what most heat is on earth) is being done by CO2.
So the cozy fireplace, heating the room, has a lot to do with the CO2 content as far as the radiant heat is concerned.
As the earth is radiating infrared heat, and O2 and N2 don’t absorb infrared, is only mostly CO2 doing the absorbing/radiating.
As an aside, I started learning about infrared light around 14 years ago when I was the GM of a roofing company.
I had always been puzzled why the “anticon” insulation we would sometimes install under the metal roof sheets has the silver shiny side pointing down towards the roof space and not up.
It turn out that nearly all of the heat in a roof space is caused by infrared radiation.
The silver shiny surface is really bad at radiating infrared light.
So it points down towards the house.
This is all happening relatively dark roof spaces.
So, the CO2 is effectively a blanket which absorbs and radiates infrared in all directions. So heat coming from the earth that hits CO2 molecules, roughly half radiates back to the earth, and the same from the sun.
The rest of the 99.96% of air is effectively invisible to infrared.
I can tell you from a year or two crawling around in roofs installing insulation (one of my first building jobs) , that infrared is very good at heating up carbon. ( Tiles, timber, etc).
So the idea that “the air is all swirling around heating or cooling” is only correct as far it has the capability of absorbing and radiating heat. Which, is mostly transmitted in the infrared spectrum.
So, whilst it’s a tiny percentage, it is making a huge difference to air’s capacity to store heat.
This was interesting
