Wind and Barometer

The air around Earth is cold.

The Sun heats the Earth.

The Earth warms the air around it.

Hot air is lighter.  It goes up.

Cold air is heavier.  It goes down.

Air is moving.

Moving air is called wind.

You can feel air moving on a windy day.

Pressure means to push on something.

If you step on a ball, you are putting pressure on it.

Air pushes on Earth.

This is called air pressure.

A barometer measures air pressure.

A barometer shows how much the air is pressing on the Earth.