Earth Science

Atmospheric Processes

Air Masses

Study Tip
The different types of air masses are like different moods. Depending on an air mass’s humidity and temperature, it can bring warm, friendly weather, or cold, icy storms.

Formation of Air Masses

An air mass is a batch of air that has a uniform temperature and humidity. An air mass acquires these characteristics from the land or water that it is above. Air masses are very large and form in high-pressure zones such as polar and tropical regions. Temperate regions are too unstable for air masses to form, creating unique weather in these areas.

Study Tip
The different types of air masses are like different moods. Depending on an air mass’s humidity and temperature, it can bring warm, friendly weather, or cold, icy storms.

Air Mass Movement

Air masses move when they are pushed by high-powered winds. Once they move, they gain new characteristics based on the area they are positioned over.

Storms are caused when an air mass moves over a region with different characteristics. For example, warm air masses moving over cold landmasses cause storms. Cold air masses tend to flow towards the equator and warm air masses tend to flow toward the poles. This helps balance the temperature of the earth.

Large air masses
Large air masses are moving
over the ocean and land.
A thunderstorm
A thunderstorm is caused when
an air mass flows over a landmass
with a different temperature.
Concept Check
  • What is an air mass?
  • How are storms formed?
  • Where do warm air masses generally flow towards?