•The atmosphere is a mixture of gases that surrounds a planet, such as Earth.•Nitrogen, oxygen, carbon dioxide•Gases can be added to and removed from the atmosphere through living organisms.• For example, animals remove oxygen when they breathe in and add carbon dioxide when they breath out.

Atmosphere

•Volcanic eruptions also add gases•Vehicles both add and remove gases.•Insulates Earth’s surface.•Slows the Earth’s surface heat loss•Keeps Earth’s temperature at which living things can survive.

Atmosphere

•Nitrogen - 78 %•volcanoes erupt •dead plants and animals decay.

•Oxygen – 21%•primarily produced by plants.

•Contains •atmospheric dust.

Composition of Atmosphere

In addition to nitrogen and oxygen, •Argon •Carbon dioxide•Methane•Water vapor make up the rest of the atmosphere.

Composition of Atmosphere

•Gravity •Atmosphere is denser near the Earth’s surface.•Atmospheric gases is located within 30 km of the surface.•Air also becomes less dense with elevation, so breathing at higher elevations is more difficult.

Air Pressure