1. Meteorology

2. I. Air Masses
Air Mass: a large body of air with uniform temperature and moisture content.

3. A. Types of Air Masses
Air masses are classified according to their source regions:
1. Polar = P = cold
2. Tropical = T = warm
3. Maritime (ocean) = m = moist
4. Continental (land) = c = dry

4. B. North American Air Masses
Polar
cP Canadian: Northern US
mP Pacific: cool water off Alaska
mP Atlantic: Greenland and Iceland

5. 2. Tropical cT: Mexico, summer only mT: Gulf Coast and Atlantic
mT Pacific: heavy rain in the winter

7. Air Mass Characteristics

8. II. Fronts
Front: boundary between air masses of different densities.

9. Types of Fronts

10. A. Types of Fronts
1. Cold Front: when a cold air mass overtakes a warm air mass.

11. Cold front storms are fast- moving, short-lived and often violent.

12. What cloud type do you get with a cold front?

13. Squall Line: long line of thunderstorms ahead of a cold front

14. Thunderstorm .... Ocracoke NC – Summer 2013

15. 2. Warm Front: warm air mass overtakes a cold air mass

17. Warm fronts usually produce nimbostratus clouds
What will the weather be like?
Precipitation over a very large area.

18. 3. Stationary Front: two air masses meet and the front moves parallel

19. Neither air mass is displaced
Little movement
Precipitation continues for long period of time

21. 4. Occluded Front: fast-moving cold front lifts warm air completely off the ground.

22. Occluded Front:

26. B. Hurricanes severe storms that form over WARM tropical oceans
tropical cyclones
LOW pressure centers
winds spiral rapidly inward
counterclockwise rotation
winds over 120 km/hr (75 mi/hr)

27. warm, moist air rises rapidly
as it condenses it releases latent heat
this increases the rate of evaporation and sustains the storm

29. Anatomy of a Hurricane Eye: Eyewall: Spiral rainbands:
calm (little or no rain)
warmest part of the storm
Eyewall:
surrounds eye
wall of thunderclouds
most rain
stongest winds
Spiral rainbands:
spiral inward to eyewall

30. Saffir-Simpson Hurricane Scale
used to classify hurricanes
divides hurricanes into five categories based on intensities of sustained winds

31. Storm surge is the most dangerous aspect of a hurricane.
Typical beach along the coast
Sea walls are built to minimize damage

32. Category 1: Minimal storm Winds: 74 to 95 mph Storm surge: Up to 5 feet

33. Category 2: Moderate storm Winds: 96 to 110 mph Storm surge: 6 to 8 feet
                                                                                                         

34. Category 3: Extensive storm Winds: 111 to 130 mph Storm surge: 9 to 12 feet

35. Category 4: Extreme storm Winds: 131 to 155 mph Storm surge: 13 to 18 feet

36. Category 5: Catastrophic storm Winds: More than 155 mph Storm surge: More than 18 feet

37. 2005 Hurricane Season First year with 28 named storms
First year with 15 Hurricanes
First year with four category hurricanes
First year with four major hurricanes hitting the U.S.

38. C. Tornadoes Smallest most violent short- lived storms
Form when thunderstorms meet high altitude winds

41. Narrow, violent funnel-shaped cyclone; a column of spiral winds that extends downward from a cloud base toward Earth

42. Joplin, Missouri May 2011

43. Joplin – Then & Now

44. Fujita Scale of Tornado Intensity

45. Before thunderstorms develop, a change in wind direction and an increase in wind speed with increasing height creates an invisible, horizontal spinning effect in the lower atmosphere.

46. Rising air within the thunderstorm updraft tilts the rotating air from horizontal to vertical.

47. An area of rotation, 2-6 miles wide, now extends through much of the storm; Most strong and violent tornadoes form within this area of strong rotation.

51. III. Weather Instruments
Measuring Air Temperature:
thermometer

53. anemometer: measures wind speed.
B. Measuring Wind Speed and Direction:
anemometer: measures wind speed.

54. wind vane: shows wind direction
The arrow always points into the wind!

55. C. Radar: can detect weather conditions by sending and receiving radio waves.

56. IV. Forecasting the Weather
Station Model: cluster of weather symbols plotted around a reporting station showing the current conditions.

60. Wind patterns around areas of HIGH and LOW pressure: