How do greenhouse gases absorb and emit radiation?

This ability to absorb and re-emit infrared energy is what makes CO2 an effective heat-trapping greenhouse gas. 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. read more

Once the extra energy has been removed by the emitted photon, the carbon dioxide stops vibrating. This ability to absorb and re-emit infrared energy is what makes CO2 an effective heat-trapping greenhouse gas. Not all gas molecules are able to absorb IR radiation. read more

It’s the fact that they absorb infrared radiation that makes them greenhouse gases. The actual mechanism by which infrared is absorbed depends on the molecules. Optical wavelengths tend to be absorbed by electron transitions between atomic orbitals. Infrared wavelengths are lower energy and are absorbed by molecular resonances. read more