3. a large body of air that has the same temperature and humidity throughout classified according to where they originate during the time the air mass is over an area, it determines the weather of that area

4. Originates over the ocean  humid air mass (m) (maritime)

5. Originates over the land  dry air mass (c) (continental)

6. Originates in cold air  cool air mass (P) (Polar)

7. Originates in warm air  warm air mass (T) (Tropical)

8. Maritime Tropical Atlantic (mT) moves northward across eastern US brings mild, cloudy winters and hot humid summers with hurricanes and thunderstorms

9. Air Masses Are Classified by Region

10. small balloon carried observatory that carries a radio transmitter that sends out signals about air pressure, temperature, and humidity

11. fronts: boundary between two air masses having different temperatures and humidity

12. warm air overtakes cool air warm air rises brings hot, humid days and precipitation over a large area

13. Formation of a Warm Front

14. Cold, dense moves into a region occupied by warm air cold air forces warm air up brings strong storms (squall) with clear days following

15. Formation of a Cold Front

16. An active cold front overtakes a warm front The cold front merges with the warm front Light precipitation can fall for several days

17. Formation of an Occluded Front

18. does not move

19. small-area storms formed by the strong upward movement of warm, moist, unstable air always accompanied by lightning, thunder, and usually rain formed from cumulonimbus clouds

20. Air-mass thunderstorm: form in warm, moist air mass occur in spring and summer- last less than 1 hour single, widely scattered

22. Frontal thunderstorm: occur in lines along a frontal surface stronger and may last several hours can produce heavy rain and flooding

24. Lightning: a discharge of electricity from a thundercloud to the ground, or cloud to cloud, or ground to cloud

25. temperature inside lightning flash can reach 28,000°C at this temperature, air expands explosively-sudden expansion makes thunder!

28. an intense tropical low- pressure area with sustained winds starting at 75 mph

30. storm surge: currents formed when hurricanes pile water up along the shore and blow it inland most damaging part of a hurricane

33. eye: central area of sinking air; 15 to 20 km wide

34. Winds most violent just outside the eye (eye wall)

35. Tropical depression: wind speeds up to 38 mph; some circular rotation at surface

37. Tropical storm: wind speeds from 39-74 mph; can be named, shows drop in pressure, distinct rotation

39. Hurricane: wind speeds up to 75 mph

43. a narrow, funnel-shaped column of spiral winds that extends downward from the cloud base and touches the ground

44. strongest winds between 360 and 500 km/hr funnel less than 500 m across always travel with a parent thunderstorm at speeds ranging from 40 to 65 km/hr

45. funnel is a mixture of clouds and dust pressure gets lower in center air flows toward the funnel and cools to dew point- drops form lowering of condensation level due to low pressure causes cloud to funnel Extremely low pressure-when it touches ground, acts like a giant vacuum

46. Waterspout: tornados over the water- weaker than tornados

49. Tornados usually occur during spring and summer and most likely occur in late afternoon

52. Fujita Scale: scale used for categorizing tornados

53. Meteorologists interpret weather information from: satellites commercial aircraft weather balloons

54. weather stations around the world Radar: electronic device that transmits radio waves in the form of a beam

56. Data is collected and put into a central computer at the National Weather Service data includes: winds, temperature, pressure, humidity, clouds, precipitation Makes a computer model (copy of the atmosphere in computer

57. Maps are made and forecasts are reported to local stations across the country Weather forecasts are issued by the Weather Service at 10 am, 4 pm, 9pm, and 4 am. Forecasts are updated more often during severe weather.

58. watch: threat of storm conditions within 24-36 hours warning: due to strike within 24 hours