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Air Masses and Fronts
Air masses take on the characteristics of the area where they form. Air masses are classified according to their temperature and moisture content § Warm air forms over tropical regions near the equator. T- Tropical § Cold air forms over polar regions. P- Polar § Wet air masses form over water m- maritime § Dry air masses from over land. c- continental 2
§ Moisture content is noted by the first letter. m – maritime – wet c – continental – dry § Temperature is noted by the second letter. P – polar – cool T – tropical - warm 3
What are the four types of air masses? § § Maritime Tropical (m. T) Maritime Polar (m. P) Continental Tropical (c. T) Continental Polar (c. P)
How do air masses move? § § The prevailing westerlies are the major wind belts in the United States. Prevailing westerlies push air masses from west to east.
Fronts A front is a boundary between two air masses of different density, moisture, and temperature, the collision often causes storms and weather changes. § A front may be 15 to 200 kilometers wide and extend as much as 10 kilometers up to the troposphere. § The kind of front that develops depends on the characteristics of the air masses and how they move. §
There are four types of fronts. § Cold Fronts. Warm Fronts. Stationary Fronts. § Occluded Fronts. § §
Cold Fronts n n Cold air mass meets a warm air mass and pushes the warm air mass out of its way. Bring thunderstorms, rain or snow. Most tornadoes develop from thunderstorms on the edge of a cold front. Cold fronts are followed by cooler drier air.
Warm Fronts l Warm air mass meets a cold air mass and pushes the cold air mass out of the way. l Brings drizzly precipitation. l Followed by clear warm weather.
Stationary Fronts n Cold air meets warm air. n Not enough force to move either front. n Many days of cloudy, wet weather.
Occluded Fronts n Warm air caught between two cold air masses. n Brings cool temperatures with large amounts of rain or snow.
Cold Front, Warm Front, Stationary Front and Occluded Front Animation http: //www. stevemcentee. com/animation 3. html Click on the link above. n 12
Section Review Questions Answer the following questions on the paper provided. 1. Describe a maritime polar (m. P) air mass, in terms of moisture and temperature. 2. What is the name of an air mass that forms over water? 3. What is the name of an air mass that forms over land? 4. What is the name of an air mass that forms in a cold region? 5. What is the name of an air mass that forms in a warm region? 6. Describe a continental tropical (c. T) air mass, Moisture and temperature. 7. The boundary between two air masses is called a ___________. 8. A cold air mass meets and pushes a warm air mass out of the way. What type of front am I? 9. A warm air mass is trapped between to cold air masses. What type of front am I? 10. A warm air mass meets and pushes a cold air mass out of the way. What type of front am I? 11. I am a front that brings drizzly rain and am followed by warm clear weather. Name me 12. A cold air mass meets a warm air but neither is very strong. They are separated and many days of wet , cloudy weather occur. 13