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)

Carbon dioxide (CO2), water vapor (H2O), methane (CH4), nitrous oxide (N2O), and a few other gases are greenhouse gases. They all are molecules composed of three or more atoms, bound loosely enough together to be able to vibrate when they absorb heat. Eventually, the vibrating molecule will emit the radiation again, and it will likely be absorbed by yet another greenhouse gas molecule. This process is called the greenhouse effect and keeps heat near the Earth's surface.

Almost all of the other gases in Earth's atmosphere are nitrogen (N2) and oxygen (O2). The two atoms in these molecules are bound together tightly and unable to vibrate, so they do not absorb heat and contribute to the greenhouse effect.

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.

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)

Only a tiny amount of the gases in Earth’s atmosphere are greenhouse gases. But they have a huge effect on climate.

There are several different types of greenhouse gases, but they all have something in common. All of them have molecules with three or more parts. The parts are stuck together pretty loosely. These molecules can hold onto heat. This makes the little parts wiggle back and forth. Eventually, the molecule will release the heat. Another greenhouse gas molecule will probably grab onto the heat that is released. This keeps heat near the Earth’s surface. It is called the greenhouse effect.