# Earth's atmosphere

## Atmosphere's composition

The composition of the atmosphere is 78% nitrogen, 21% oxygen, 1% other mainly 0.9% Argon.

## How is the atmosphere useful?

1: Protects us from harmful sun rays

2: Causes the greenhouse effect heating the planet

3: The mesosphere burns meteoroids causing them to do less harm

## Air pressure

Although we don't feel it much air has mass which is effected from pressure. Pressure is the weight of one object pushing on another object. The formula for calculating is mass/volume=density. Airpressure can also be measured with a barometer. Their are two kinds of barometers mercury and aneroid both measures air pressure.

## Air pessure, density, and altitude

The relationship between air pressure and altitude is reverse. As the altitude goes up air pressure goes down. It is the same with air density. As the altitude rises the density goes down. This is because there are more layers of air above in a lower region. This causes more pressure on the area from the layers above.

## Troposphere-change

9-16 kilometers above the Earth's surface.

The level of the atmosphere where weather occurs.

Contains 3/4 of the atmosphere's mass.

50 kilometers above the Earth's surface.

The layer of the atmosphere containing the ozone. The ozone protects the planet from ultra violet sunrays.

The higher level in the stratosphere the higher temperature.

## Mesosphere-middle

50-80 kilometers above the Earth's surface.

The mesosphere is the layer of the atmosphere where meteoroids burn up causing them to cause less destruction of Earth.

## Thermosphere-heat

80 kilometers above the Earth's surface.

0.001 of the atmosphere's mass.

Has no definate outer limit.

The layer where satilites orbit.

Made up of the ionosphere and the exosphere.

## Ionosphere and Exosphere

Ionosphere: 80-400km above the Earth's surface where energy charged particles (ions) bounce off radio waves to Earth causing auroras.

Exosphere: 1,000nds of kilometers above the Earth's surface and goes out into space.