Summary:
- An air mass is a large body of air that has about the same conditions throughout.
- The characteristics of an air mass depend on where the air mass formed.
- Most air masses form over polar or tropical regions.
- They may form over continents or oceans.
- Air masses move when they are pushed by high level winds.
- Many air masses move toward the northeast over the U.S.
- This is the same direction that global winds blow.
- Moving air masses cause the weather to change.
- For example, a warm air mass moving over cold ground may cause an inversion.