How the atmosphere supports life

• The gases for natural processes supports life as the gases in the atmosphere carbon, oxygen, hydrogen and nitrogen. These are needed to make the biological molecules used by living organisms. They are extracted from the atmosphere as N2, O2, CO2 and H2O. Carbohydrates, lipids and proteins all contain carbon, oxygen and hydrogen and proteins contain nitrogen.
• The absorption of electromagnetic radiation from the Sun supports life on Earth as much of the biologically damaging radiation in the 'Solar Wind' is prevented from reaching Earth by the upper atmosphere. Most of the UV that passes through the upper atmosphere is prevented by reaching the surface by monatomic, diatomic and triatomic oxygen in the ozone layer in the stratosphere. The ozone layer absorbs UV light, producing a dynamic equilibrium of chemical reactions which form and destroy ozone.
• The delaying the escape of infrared energy supports the Earth as much of the incoming visible light is absorbed, converted to heat and re-emitted as infrared energy. Naturally occurring atmospheric gases absorb this infrared energy, convert it to heat and increase the temperature of the atmosphere. This raises the temperature of the Earth in two ways: the warm atmosphere emits infrared energy which is absorbed by the Earth's surface or the warm atmosphere reduces heat loss by conduction from land and the oceans.
• Heat distribution supports life on Earth as most of the energy from the Sun, absorbed at the Earth's surface, is absorbed in tropical regions. The warm surface heats the atmosphere above and this heat is distributed to higher latitudes by warm winds, such as the south-westerly winds that bring heat energy to the UK from the Caribbean Sea.
• The ocean currents supports life on Earth as winds blowing over the oceans create currents that distribute heat by carrying warm water from tropical areas to higher latitudes, such as the North Atlantic Conveyor. These currents can also distribute dissolved nutrients.
• Transport of water vapour supports life as winds transport water vapour to areas that would otherwise get little or no precipitation.
• Atmospheric pressure controls the ease with which water molecules can evaporate and escape from the water surface. If atmospheric pressure was much lower there would be no liquid water on Earth.