The greenhouse effect
Without greenhouse gasThe gases responsible for global warming - carbon dioxide, methane, nitrous oxide and CFCs (chlorofluorocarbons). in its atmosphereThe layers of gases that surround the Earth. The important gases in the atmosphere are nitrogen, oxygen and carbon dioxide., the Earth would be much colder on average than it is now. Greenhouse gases:
- absorb energyThe capacity of a system to do work or the quantity required for mechanical work to take place. Measured in joules (J). For example, a man transfers 100 J of energy when moving a wheelbarrow. transferred as infrared radiationElectromagnetic radiation emitted from a hot object. from the Earth鈥檚 surface
- release infrared radiation in all directions, which keeps the Earth warm
The diagram gives more details about this process, called the greenhouse effectThe retention of heat in the atmosphere caused by the build-up of greenhouse gases..
- electromagnetic radiation at most wavelengths passes through the Earth's atmosphere
- the Earth absorbs most of the radiation and warms up
- the Earth radiates energy as infrared radiation
- some of the infrared radiation goes into space
- some of the infrared radiation is absorbed by greenhouse gases in the atmosphere
- the lower atmosphere warms up
Question
Name three greenhouse gases.
Carbon dioxide, methane and water vapour.