Why do greenhouse gases only absorb infrared radiation?
Molecules are constantly in motion, colliding with other gas molecules and transferring energy from one molecule to another during collisions. In the more-complex, real-world process, a CO2 molecule would most likely bump into several other gas molecules before re-emitting the infrared photon.
Which wavelength of radiation do greenhouse gases absorb most effectively?
Greenhouse gases in the atmosphere (such as water vapor and carbon dioxide) absorb most of the Earth’s emitted longwave infrared radiation, which heats the lower atmosphere.
Why do greenhouse gases absorb infrared radiation from the Earth but not the sun?
Greenhouse Gases. You have already learned that Earth’s atmosphere is composed primarily of nitrogen and oxygen. These gases are transparent to incoming solar radiation. They are also transparent to outgoing infrared radiation, which means that they do not absorb or emit solar or infrared radiation.
Why do molecules absorb IR radiation?
For a molecule to absorb IR, the vibrations or rotations within a molecule must cause a net change in the dipole moment of the molecule. If the frequency of the radiation matches the vibrational frequency of the molecule then radiation will be absorbed, causing a change in the amplitude of molecular vibration.
How do greenhouse gases get trapped in the atmosphere?
Burning fossil fuels like coal and oil puts more carbon dioxide into our atmosphere. Too much of these greenhouse gases can cause Earth’s atmosphere to trap more and more heat. This causes Earth to warm up.
How does the absorption of IR light by a greenhouse gas lead to an increase in atmospheric temperature?
As the percentage of some greenhouse gases, such as carbon dioxide, increases in the atmosphere, the average temperature also increases. Those items, in turn, emit infrared radiation that is primarily absorbed by gases and water vapor in the atmosphere, increasing its temperature.
Why do greenhouse gases absorb heat?
These gas molecules all are made of three or more atoms. The atoms are held together loosely enough that they vibrate when they absorb heat. Eventually, the vibrating molecules release the radiation, which will likely be absorbed by another greenhouse gas molecule. This process keeps heat near the Earth’s surface.