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Vocabulary on Weather

1. weather

 The condition of Earth's atmosphere at a particular time and place.

2. climate

 The average weather conditions over a large geographic area that extends over a long period of time.

3. air mass

 A large body of air that has similar temperature, humidity and air pressure throughout.

4. front

 The boundary where unlike air masses meet but do not mix.

5. Tropical air mass

 A warm air mass that forms in the tropics (near the equator) and has low pressure

6. Polar air mass

 A cold air mass that forms in the poles (above 50šN and below 50šS)and has high pressure

7. Maritime air mass

 A humid air mass that forms over oceans

8. Continental air mass

 A dry air mass that forms over land

9. Maritime Tropical

 Wet, hot air masses - Usually brings summer showers and thunderstorms in the eastern United States.  In winter, it brings heavy rain or snow.

10. Maritime Polar

 Wet, cold air masses.  These affect the west coast more than the east.  They bring fog, rain and cool temperature.

11. Continental Tropical

 Dry, hot air masses. They affect mostly the southwest and Mexico bringing hot, dry weather.

12. Continental Polar

 Dry cold air masses. They bring bitterly cold weather with low humidity.  In summer they are much milder

13. How do air masses move in the continental United States?

 In the United States air masses are usually moved by either the Jet Streams or the Prevailing Westerlies.  Both of these winds carry air masses from West to East.

14. Cold Fronts

 This occurs when a fast moving cold air mass runs into a slow moving warm air mass.  Since they move quickly they bring sudden weather changes, including thunderstorms.  After it passes an area there will be colder, drier air and clear skies.

15. Warm Fronts

 This occurs when a fast-moving warm air mass overtakes a slowly moving cold air mass.  Clouds and/or precipitation occur.  After it passes an area there will be warm and humid air.

16. Stationary Fronts

 When a warm air mass meets a cold air mass and neither is moving very fast.  The warm air and cool air meet causing condensation to occur, which causes precipitation.  This remains over an area for a long period of time, possibly a few days of clouds and precipitation.

17. Occluded Fronts

 This is when a warm air mass becomes trapped between two cooler air masses. 

Three fronts come together.  It forms in stages.  It begins with a stationary front between a cold and a warm air mass.  Then a cold front comes through faster and lifts up the warm air.

Very heavy rains, severe weather (thunderstorms and strong winds)