Atmosphere Composition and Air Pressure

Atmosphere

The layer of gases surrounding Earth.

It is essential for life, composed mainly of nitrogen and oxygen.

Air has weight, because it is made up of atoms and molecules, which have mass!

How does the atmosphere support life on Earth?

1. By trapping energy from the sun, the atmosphere keeps most of Earth’s surface warm enough for water to exist as a liquid.

2. Earth’s atmosphere protects living things from dangerous radiation from the sun.

3. The atmosphere prevents Earth’s surface from being hit by meteoroids.

Gravity

Force holding the atmosphere around Earth

Nitrogen

Most abundant gas in the atmosphere. This gas makes up about 78% of the atmosphere

Oxygen

Second most abundant gas in the atmosphere. This gas makes up about 21% of the atmosphere

Density

Amount of mass in a given volume. Density = mass/volume

Pressure

The force pushing on an area or surface.

Air has pressure because it is made up of atoms and molecules, which have mass, so air must have mass!

Altitude

Distance from sea level

Water Vapor

Water in gas form

Barometer

Instrument used to measure air pressure

Humidity

Amount of moisture in the air

What is the relationships between altitude and air pressure?

As altitude increases, air pressure decreases.

Gravity pulls air molecules closer to Earth’s surface, so there are more molecules and more pressure at sea level.

What is the relationship between temperature and air pressure

As temperature increases, air pressure decreases

When heat is applied, air molecules speed up and spread apart, causing less pressure!