What puts the greenhouse in gas
All molecules of greenhouse gas – ozone, carbon dioxide, water vapour and the rest – have at least three atoms. These molecules capture and absorb radiation more easily than a two-atom molecule like nitrogen or oxygen, making them the prime culprits in global warming. If the/re so effective, why don't these molecules catch energy on its way down rather than on its way up? Some incoming sunlight is indeed absorbed, but a large portion the heat we feel in the air actually comes up from the ground (try standing in a car park on a hot day and you'll get the picture). The energy that radiates upward is in the infrared – a longer wavelength range than most of the sunlight that warmed the ground in the first place. Since molecules of a three-atom gas can vibrate and rotate in sync with infrared radiation, they can absorb its energy much more easily than can two-atom gases.The greenhouse molecules can then emit energy in all directions, some of which goes towards the surface. Thus, you have the greenhouse effect: radiation comes in, but it can't all get out (very easily, anyhow).