The greenhouse effect

Without greenhouse gases in its atmosphere, the Earth would be about 18°C colder on average than it is now. That would make it too cold to support life as we know it.

Greenhouse gases present in the atmosphere include:

These greenhouse gases:

  1. Absorb heat radiated from the Earth
  2. then release energy in all directions, which keeps the Earth warm

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

Image and text to explain how the greenhouse effects works.How 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
Question

Name three greenhouse gases.

Carbon dioxide, methane and water vapour.