Weather describes the state of the atmosphere at a particular place and time.
The atmosphere is a mixture of gases (including oxygen) that exists above the Earth. It protects the Earth by blocking dangerous rays from the sun and trapping heat. The five layers of the atmosphere are:
- Troposphere: This is the layer closest to the Earth. Most weather occurs in the troposphere.
Changes in weather are caused by moving air in the atmosphere. Air movement occurs because of differences in air pressure.
Air pressure is caused by the collective weight of air molecules. High air pressure results in the movement of air in a slow, downward direction. Low air pressure results in the movement of air in a slow, upward direction.
As the air moves, it redistributes heat energy from the sun.