1. ATM OCN 100 Summer 2002 1 ATM OCN 100 - Summer 2002 LECTURE 12 (con’t.) CLOUD OBSERVATIONS & CLASSIFICATION A. INTRODUCTION CLOUDS – SIGNPOSTS IN THE SKY B. CLOUD OBSERVATIONS & MEASUREMENTS C. CLOUD TYPES – CLOUD CLASSIFICATION SCHEME

2. ATM OCN 100 Summer 2002 2 Announcements u Homework 3 is: –Please Pick up yours in front (at end of class). –Key will be posted on the Web at: –http://www.aos.wisc.edu/~hopkins/aos100/homework; http://www.aos.wisc.edu/~hopkins/aos100/homework u First Hour Exam –If you have not picked up exam, please do so! –An exam statistics page is posted at: http://www.aos.wisc.edu/~hopkins/aos100/exams; http://www.aos.wisc.edu/~hopkins/aos100/exams u Did you forget to turn your clocks back 1 hour on Sunday?!

3. MADISON’S CURRENT WEATHER at 900 AM CST MON OCT 29 2001 Updated twice an hour at :05 and :25 Sky/Weather: MOSUNNY Temperature: 49 F (9 C) Dew Point: 36 F (2 C) Relative Humidity: 61% Wind: CALM MPH Barometer: 30.39R

4. ATM OCN 100 Summer 2002 4 CURRENT IR

5. ATM OCN 100 Summer 2002 5 CURRENT VISIBLE

6. ATM OCN 100 Summer 2002 6 CURRENT WATER VAPOR

7. ATM OCN 100 Summer 2002 7 Surface Weather Map from Today with Isobars & Fronts

8. ATM OCN 100 Summer 2002 8 Current Temperatures ( o F) & Isotherms

9. ATM OCN 100 Summer 2002 9 Current Dewpoints ( o F)

10. ATM OCN 100 Summer 2002 10 Current Precipitable Water (in mm) from GOES Satellites

11. ATM OCN 100 Summer 2002 11 Last 24 hrs in Madison

12. ATM OCN 100 Summer 2002 12 IFR – Instrument Flight Rules Red Dots: Ceiling < 1000 ft or Visibility < 3 miles

13. ATM OCN 100 Summer 2002 13 Tomorrow’s 7AM Forecast

14. MADISON’S CURRENT WEATHER Madison Weather at 1000 AM CDT 16 JUL 2002 Updated twice an hour at :05 and :25 Sky/Weather: SUNNY Temperature: 79 F (26 C) Dew Point: 60 F (15 C) Relative Humidity: 52% Wind: SW6 MPH Barometer: 30.13F (1020.3 mb)

15. ATM OCN 100 Summer 2002 15 Last 24 hrs in Madison FOG

16. ATM OCN 100 Summer 2002 16 CURRENT VISIBLE T.S. Arthur Winds: 60 mph

17. ATM OCN 100 Summer 2002 17 T.S. Arthur CURRENT IR

18. ATM OCN 100 Summer 2002 18 Yesterday’s High Temperatures ( ° F)

19. ATM OCN 100 Summer 2002 19 Current Surface Weather Map with Isobars (“iso” = equal & “bar” = weight), Fronts and Radar

20. ATM OCN 100 Summer 2002 20 Current Surface Winds with Streamlines & Isotachs (“iso” = equal & “tach” = speed) L L H H LL H H L L H L L H

21. ATM OCN 100 Summer 2002 21 Yesterday’s High Temperatures ( o F) – (1961-90) Average High Temperatures

22. ATM OCN 100 Summer 2002 22 Current Temperatures ( o F) – 24 Hrs Ago Cold Advection + Drier Air

23. ATM OCN 100 Summer 2002 23 Current Temperatures ( ° F) & Isotherms (“iso” = equal +”therm” = temperature)

24. ATM OCN 100 Summer 2002 24 Current Dewpoints ( o F)

25. ATM OCN 100 Summer 2002 25 IFR – Instrument Flight Rules Red Dots: Ceiling < 1000 ft or Visibility < 3 miles

26. ATM OCN 100 Summer 2002 26 Current Apparent Temperatures ( o F)

27. ATM OCN 100 Summer 2002 27 Forecast Heat Indices

28. ATM OCN 100 Summer 2002 28 Tomorrow AM Forecast Map

29. ATM OCN 100 Summer 2002 29 Announcements u Homework #3 is due next Thurs. 18 July 2002 u If you have ??, please see me.

30. ATM OCN 100 Summer 2002 30 ATM OCN 100 - Summer 2002 LECTURE 12 CLOUD OBSERVATIONS & CLASSIFICATION A. INTRODUCTION CLOUDS – SIGNPOSTS IN THE SKY – What can be learned from clouds? – Is it partly cloudy or partly sunny? – How are clouds classified?

31. ATM OCN 100 Summer 2002 31 CLOUDS - SIGNPOSTS IN THE SKY u Atmospheric moisture content; u Air temperatures aloft; u Atmospheric stability; u Tracer for winds aloft (speed & direction) and wind shear [speed/direction change with height].

32. ATM OCN 100 Summer 2002 32 B. OBSERVATIONAL MEASUREMENTS OF CLOUDS u Cloud Amount or Sky Cover – fraction of sky covered by a cloud; – based on visual estimates or measurements.

33. ATM OCN 100 Summer 2002 33 B. CLOUD OBSERVATIONS (con’t.) u Cloud Heights & Ceilings – Height of cloud base; – Based upon visual estimates or measurements.

34. ATM OCN 100 Summer 2002 34 C. CLOUD TYPES - CLOUD CLASSIFICATION SCHEME u Historical – Luke Howard in early 19th century. u Basis for Modern Traditional Cloud Classification Scheme – Appearance – Height

35. ATM OCN 100 Summer 2002 35 C. CLOUD CLASSIFICATION SCHEME (con’t.) u The Nature of Cloud Types – Layer or Stratiform Clouds F Layer forms indicate gentle uplift. – Heaped or Cumuliform Clouds F Puffy forms indicate vigorous uplift.

36. ATM OCN 100 Summer 2002 36 CLOUD TYPES [based upon International Cloud Atlas (WMO)] See Table 7.1 Moran & Morgan, 1997

37. ATM OCN 100 Summer 2002 37 HIGH CLOUDS > 20,000 ft (> 6 km) “Cold clouds” with ice crystals See Table 7.1 Moran & Morgan, 1997

38. ATM OCN 100 Summer 2002 38Cirrus

39. 39Cirrus

40. 40 Cirrus

41. 41 Cirrostratus

42. 42 Cirrostratus (Cs) Made of a thin, transparent layer of (all ice) high clouds. Halos are common with this cloud type.

43. ATM OCN 100 Summer 2002 43 Cirrostratus

44. 44 Cirrocumulus

45. 45 Cirrocumulus

46. 46 Cirrocumulus

47. 47 Cirrocumulus (Cc) Note the clumpy rows – due to wind shear (also all ice)

48. ATM OCN 100 Summer 2002 48 MIDDLE CLOUDS 6500 to 20,000 ft (2 – 6 km) “Cold clouds” with supercooled water droplets See Table 7.1 Moran & Morgan, 1997

49. ATM OCN 100 Summer 2002 49 Altocumulus

50. 50 Altocumulus (Ac) Remember…cumulus means puffy. (Can be a mix of ice & water)

51. ATM OCN 100 Summer 2002 51 Altocumulus

52. 52 Altostratus

53. 53 Altostratus

54. 54 Altostratus

55. 55 Altostratus (As) Another transparent layer….this one is at mid levels and can be made up of ice and water

56. ATM OCN 100 Summer 2002 56 LOW CLOUDS 0 – 6500 ft (0 – 2 km) “Warm clouds” with water droplets See Table 7.1 Moran & Morgan, 1997

57. ATM OCN 100 Summer 2002 57 Stratus

58. 58 Stratus

59. 59 Nimbostratus

60. 60 Stratocumulus

61. 61 Stratocumulus (Sc) (con’t.) Stratocumulus layers are thin, but can be extremely dense, as seen from above.

62. ATM OCN 100 Summer 2002 62 VERTICALLY DEVELOPED CLOUDS 0 – 10,000 ft ( 0 – 3 km) See Table 7.1 Moran & Morgan, 1997

63. ATM OCN 100 Summer 2002 63 Cumulus

64. 64 Cumulus (Fair Weather) (Cu) Note the puffiness of the clouds. Also, they are rather isolated, although it may not appear that way on the horizon.

65. ATM OCN 100 Summer 2002 65 Cumulonimbus

66. 66 Cumulonimbus

67. 67 Cumulonimbus (Cb) Notice the anvil aloft! This cloud is probably nearly 100 miles away. They are huge!!! ANVIL RAIN SHAFT Approximate tropopause (~ 6 miles high)

68. ATM OCN 100 Summer 2002 68 Cumulonimbus

69. 69 OTHER SPECIAL CLOUDS Cloud Species See Table 7.2 Moran & Morgan, 1997

70. ATM OCN 100 Summer 2002 70 Cumulus Congestus

71. ATM OCN 100 Summer 2002 71 Cumulus Congestus

72. ATM OCN 100 Summer 2002 72 Cumulus Congestus These may be seen in the early afternoon on a humid day. If so, Cumulonimbus will most likely form later in the day.

73. ATM OCN 100 Summer 2002 73 Mammatus

74. 74 Altocumulus Lenticularis

75. ATM OCN 100 Summer 2002 75 Mountain Wave Clouds Fig. 7.24 Moran & Morgan (1997)

76. ATM OCN 100 Summer 2002 76 Mountain Cap Clouds Air can be lifted by the flow against a mountain to form these clouds.

77. ATM OCN 100 Summer 2002 77 Altocumulus Lenticularis

78. ATM OCN 100 Summer 2002 78 Contrails - Condensation Trail

79. ATM OCN 100 Summer 2002 79 Contrails – (9 Oct 2000 NASA)

80. ATM OCN 100 Summer 2002 80 C. CLOUD TYPES (con’t.) u Cloud Identification Aids – Texture – Cloud base estimation – Size of features – Shades of gray – Existence of optical phenomena u Gallery of Specific Cloud Types

81. ATM OCN 100 Summer 2002 81 D. CLOUD CLIMATOLOGY u Geographical variation of clouds u Seasonal variation of clouds

82. ATM OCN 100 Summer 2002 82 Average Cloudiness -- Annual

83. ATM OCN 100 Summer 2002 83 Average Cloudiness -- July

84. ATM OCN 100 Summer 2002 84 Average Cloudiness -- January

85. ATM OCN 100 Summer 2002 85 REVIEW of CLOUD TYPES [based upon International Cloud Atlas (WMO)] See Table 7.1 Moran & Morgan, 1997