This animation shows how a carbon dioxide molecule vibrates when it absorbs heat. Click on image for full size (116 Kb) Courtesy of UCAR (LEARN and COMET)

Even though only a tiny amount of the gases in Earth’s atmosphere are greenhouse gases, they have a huge effect on climate.

There are several different types of greenhouse gases. The major ones are carbon dioxide, water vapor, methane, and nitrous oxide. All of these have molecules with three or more atoms. The atoms are held together loosely enough that they vibrate when they absorb heat. Eventually, the vibrating molecule will release the radiation. The radiation will likely be absorbed by another greenhouse gas molecule. This process, which keeps heat near the Earth’s surface, is called the greenhouse effect.

Almost all of the other gases in Earth’s atmosphere are nitrogen and oxygen. The two atoms in these molecules are bound together tightly and unable to vibrate, so they cannot absorb heat and contribute to the greenhouse effect.