Weather Systems

1. Weather Systems

2. Air mass • Definition- large body of air that sits over land/water for many days. • The air takes on the characteristics of the land or water below it.

3. Characteristics of an Air Mass • Air masses are classified by a combination of two words: the first word represents where the air mass forms, and the second represents temperature. • Continental: forms over land, air becomes dry • Maritime: forms over water, air becomes moist • Tropical: forms near equator, air becomes warm • Polar: form far from equator, air becomes cool

4. What is my name? • This type of air mass forms over land and near the equator. • This type of air mass forms over water and far away from the equator. • This type of air mass forms over land and far from the equator. • This type of air mass forms over water and near the equator. • http://player.discoveryeducation.com/index.cfm?guidAssetId=EF8249F5-456A-41F1-9C64-508D9AFDE2C4&blnFromSearch=1&productcode=DSC

5. FRONTS • Definition- A front is the boundary (space) in between two air masses • When two air masses meet, weather is created and will change! • Some of those changes include: cloud formation, stormy weather, precipitation • After the air mass moves in, you experience the temperature and humidity of that air mass.

6. Types of fronts • Cold Front: cold air mass pushes a warm air mass causing the warm air to rise. • As warm air rises it condenses forming tall clouds! • Can bring heavy rain and stormy weather

7. Types of fronts cont… • Warm front: Forms when a warm air mass pushes a cold air mass. Warm air slowly rises over the cold air and the moisture from the warm air condenses into flat clouds. Brings many hours of light rain or snow. http://www.mesoscale.iastate.edu/agron206/animations/05_cnWfronts.html

8. Types of fronts cont… • Stationary front: occurs when two air masses push against each other without moving. Can become either a warm or cold front depending on which air mass moves first. http://player.discoveryeducation.com/index.cfm?guidAssetId=5CDF74DF-97DC-4BA1-996A-C13E68455E0E&blnFromSearch=1&productcode=DSC

9. Pressure systems • Definition- an area where there is either very high pressure or very low pressure in that region. • Symbolized with a H or an L on a weather map

10. HIGH PRESSURE SYSTEM • At a high pressure center, air sinks down slowly. • Air spreads out to areas of low pressure. • High pressure system is formed when air moves all the way around a high pressure center. Usually very large and change slowly. • Generally brings clear skies, calm air, and gentle breezes because as air sinks it warms causing water droplets to evaporate so clouds disappear.

11. LOW PRESSURE SYSTEM • Large weather system that surrounds a center of low pressure. Air moves inward and upwards to higher altitudes. The faster the movement, the stronger the system. • Rising air produces stormy weather and can form when two air masses meet. • Tropical storms, hurricanes, storm surges, blizzards, snowstorms, and ice storms are all created from low pressure systems.

12. Pressure system cont.. • Barometer measures air pressure http://player.discoveryeducation.com/index.cfm?guidAssetId=EC320CD3-D1D7-4A22-AD71-435316547A75&blnFromSearch=1&productcode=US