1. Weather

3. classified according to where they originate
air mass
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
Which one affects us?
Maritime Tropical Atlantic (mT)
moves northward across eastern US
brings mild, cloudy winters and hot humid summers with hurricanes and thunderstorms

10. radiosonde:
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
Types of Fronts

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

14. cold air overtakes warm air cold air forces warm air up
cold front
cold air overtakes warm air
cold air forces warm air up
brings strong storms (squall) with clear days following

16. two cold masses sandwich a warm mass warm air rises between them
occluded front
two cold masses sandwich a warm mass
warm air rises between them
brings strong winds and heavy rains

17. stationary front
does not move

18. always accompanied by lightning, thunder, and usually rain
Thunderstorms
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

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

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

23. All thunderstorms produce lightning!
a discharge of electricity from a thundercloud to the ground, or cloud to cloud, or ground to cloud

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

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

30. most damaging part of a hurricane
parts of a hurricane:
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. Eye of hurricane Floyd

35. Winds most violent just outside the eye

36. Check out this website!

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

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

41. Hurricane: wind speeds up to 75 mph

43. Movement of Air in a Hurricane

44. There are sometimes gaps in between these bands where no rain is found
There are sometimes gaps in between these bands where no rain is found. In fact, if one were to travel between the outer edge of the hurricane to its center, one would normally progress from light rain to dry back to slightly more intense rain again over and over with each period of rainfall being more intense and lasting longer until reaching the eye. Upon exiting the eye and moving towards the edge of the hurricane, one would see the same events as they did going in, but in opposite order.

45. A schematic of this banding feature can be seen in the diagram above
A schematic of this banding feature can be seen in the diagram above. The thunderstorms are now organized into regions of rising and sinking air. Most of the air is rising, but there is a small amount found in between the thunderstorms that is sinking.

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

56. 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

57. 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

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

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

64. Fujita Scale: scale used for categorizing tornados

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

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

69. 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

70. 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.

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