The greenhouse effect

Without greenhouse gases in its atmosphere, the Earth would be much colder on average than it is now. Greenhouse gases:

  • absorb energy transferred as infrared radiation from the Earth’s surface
  • release infrared radiation in all directions, which keeps the Earth warm

The diagram gives more details about this process, called the greenhouse effect.

The greenhouse effectHow the greenhouse effect works
  1. electromagnetic radiation at most wavelengths passes through the Earth's atmosphere
  2. the Earth absorbs most of the radiation and warms up
  3. the Earth radiates energy as infrared radiation
  4. some of the infrared radiation goes into space
  5. some of the infrared radiation is absorbed by greenhouse gases in the atmosphere
  6. the lower atmosphere warms up

Name three greenhouse gases.

Carbon dioxide, methane and water vapour.