The Main Greenhouse Gases
- When radiation from the sun hits the earth, it is radiated back from the earth's surface as long-wave radiation
- A greenhouse gas is a gas that absorbs this re-radiated radiation, trapping it in the earth's atmosphere so that it is not lost to space
- Greenhouse gases in the atmosphere have a similar effect to the glass in a greenhouse, hence the term greenhouse gas, and their effect being known as the greenhouse effect
- The greenhouse effect is important to ensure that Earth is warm enough for life; if it were not for the insulating effects of greenhouse gases, Earth would see similar dramatic temperature fluctuations to its neighbouring planets
- Temperatures on Mars range between 20°C and −153°C
- There are many greenhouse gases, and those that contribute most to the greenhouse effect are:
- Water vapour
- Carbon dioxide
- Water vapour enters the atmosphere when it evaporates from the surface of the oceans, and when it is released by transpiration
- Carbon dioxide enters the atmosphere when living organisms respire, or when organic matter or fossil fuels are burned