Chapter 20

1. Chapter 20 Weather

2. Section 20.1 • Meteorology- study of weather

3. Air mass: - large body of air, in the lower troposphere. -May be several kilometers in diameter and height -has similar temperature and humidity through out the air mass

5. -the temperature and humidity of the air mass depends on where the air mass originates -air masses from the poles are cold and air masses from the tropics are warm. -Air masses formed over land will be dry - Air masses formed over water will be humid

6. As an air mass moves, the temperature will begin to change ex: Air masses moving south from Canada will slowly warm up

7. 5 types of air masses • Classified by where they originate -Temperature is determined by where it began: -Arctic, Polar, or Tropical -Humidity is determined if air mass began over sea (maritime) or over land (continental)

8. Continental Arctic cA • Originates over arctic land • Extremely cold, it may warm up slightly • Very dry air

9. Continental Polar cP • Originates over Alaska and Canada • A bit warmer than cA • Air is dry, but it will pick up moisture as it passes over the great lakes, bringing snow on the other side. This is called lake effects snow

12. Maritime Polar mP • Originates over ocean in high latitudes so it is cold and damp • b/c the ocean is warmer than the continents the mP air masses are slightly warmed than the cP air masses

13. These air masses cause the fog and damp weather on the west coast. • mP air masses from the Northern Atlantic may cause Nor’easters on the east coast

16. Maritime tropical mT • Air masses over warm topical oceans • Air is warm and humid • Can cause summer time thunder storms

17. Continental Tropical cT • Originates over hot and dry deserts • May begin as a maritime air mass, but becomes dry as it passes over a mountain range • In the summer it creates heat waves w/o thunderstorms • Can cause drought conditions