The greenhouse effect refers to the process where certain gasses, known as "greenhouse gasses", trap heat in the Earth's atmosphere. The image to the right depicts this effect. Solar radiation from the sun is directed towards the Earth. The Earth absorbs around half of the radiation, which heats it up. Some of the solar radiation is released through the atmosphere, back into space. Greenhouse gasses trap some of this radiation trying to escape, heating up the atmosphere and Earth even more. As humans emit more green house gasses, an excessive amount of heat is trapped in the atmosphere, leading to global warming.