1. Atmosphere
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.

2. 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.

3. Composition of Atmosphere
Nitrogen - 78 %
volcanoes erupt
dead plants and animals decay.
Oxygen – 21%
primarily produced by plants.
Contains
atmospheric dust.

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

5. Air Pressure 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.