Composition of the Atmosphere

Weather Weather- the condition of Earth’s atmosphere at a particular time and place Atmosphere- the later of gases that surround the planet

The atmosphere makes conditions suitable for living things It contains oxygen and other gases living things need to live It keeps Earth’s surface warm enough for water to exist as a liquid Protects living things from radiation from the sun Prevents the surface from being hit by most meteoroids

Composition of the Atmosphere

Nitrogen Most abundant gas in the atmosphere Is essential to living things Is found in proteins Is needed for growth and repair of cells Most living things cannot obtain nitrogen directly from the air

Oxygen Second most abundant gas in the atmosphere Plants and animals take it directly from the air Is needed to release energy from food Is needed for fuels to burn It forms ozone when it interacts with lightning

Carbon Dioxide Is essential to life Plants must have Carbon Dioxide to produce food Animals give carbon dioxide off as a waste product Burning fuels release carbon dioxide

Other Gases Oxygen and nitrogen make up 99% of dry air Carbon Dioxide and argon make up most of the other 1% The remaining gases are called trace gases because only small amounts of them are present

Water Vapor In reality, air is not dry because it contains water vapor Water vapor- water in the form of a gas It is invisible and is not the same as steam

Water Vapor Cont. The amount of water vapor in the air varies from place to place It plays an important role in the weather Clouds form when water vapor condenses out of the air to form tiny droplets of liquid water or crystals of ice. The droplets or crystals fall as rain or snow if they become large enough.

Particles Air contains tiny solid and liquid particles of dust, smoke, salt, and other chemicals