1. AVIATION WEATHER
CLOUDS

3. CLOUD TYPES Latin Root Translation Example
Cumulus cumulating, heap Fair-Weather Cumulus Stratus layer, straight Altostratus
Cirrus curl of hair, horse tail Cirrus
Nimbus rain Nimbostratus
Alto high Altocumulus
Pileus Skull cap Smooth tops
High-level clouds=20,000 feet and higher, cirrus, cirrostratus, cirrocumulus
Mid-level clouds=6,500 to 20,000 feet, altostratus, altocumulus, cumulonimbus
Low-level clouds=clouds below 6,500 feet, stratus, stratocumulus
Clouds with vertical development

4. Cirrus Clouds
thin and wispy
The most common form of high-level clouds are thin and often wispy cirrus clouds.
Typically found at heights greater than 20,000 feet, cirrus clouds
are composed of ice crystals that originate from the freezing of super-cooled
water droplets. Cirrus generally occur in fair weather and point in the direction of
air movement at their elevation.

5. sheet-like and nearly transparent
Cirrostratus Clouds
sheet-like and nearly transparent
Sometimes the only indication of their presence is given by an observed halo around
the sun or moon. Halos result from the refraction of light by the cloud's ice crystals.
Cirrostratus clouds, however, tend to thicken as a warm front approaches, signifying
an increased production of ice crystals. As a result, the halo gradually disappears and
the sun (or moon) becomes less visible.

6. parallel bands or rounded masses
Altocumulus Clouds
parallel bands or rounded masses
Altocumulus may appear as parallel bands (top photograph) or rounded masses
(bottom photograph). Typically a portion of an altocumulus cloud is shaded, a
characteristic which makes them distinguishable from the high-level cirrocumulus.
Altocumulus clouds usually form by convection in an unstable layer aloft, which may
result from the gradual lifting of air in advance of a cold front. The presence of
altocumulus clouds on a warm and humid summer morning is commonly followed
by thunderstorms later in the day.

7. dark, low-level clouds with precipitation
Nimbostratus Clouds
dark, low-level clouds with precipitation
Nimbostratus are dark, low-level clouds accompanied by light to moderately falling
precipitation. Low clouds are primarily composed of water droplets since their
bases generally lie below 6,500 feet. However, when temperatures are cold enough,
these clouds may also contain ice particles and snow.

8. low, lumpy layer of clouds
Stratocumulus Clouds
low, lumpy layer of clouds
Stratocumulus clouds generally appear as a low, lumpy layer of clouds that is
sometimes accompanied by weak intensity precipitation. Stratocumulus vary in
color from dark gray to light gray and may appear as rounded masses,
rolls, etc., with breaks of clear sky in between

9. Fair Weather Cumulus Clouds puffy cotton balls floating in the sky
Fair weather cumulus are fueled by buoyant bubbles of air, or thermals, that rise
upward from the earth's surface. As they rise, the water vapor within cools and
condenses forming cloud droplets. Young fair weather cumulus have sharply
defined edges and bases while the edges of older clouds appear more ragged, an
artifact of cloud erosion. Evaporation along the cloud edges cools the surrounding
air, making it heavier and producing sinking motion (or subsidence) outside the cloud.

10. reaching high into the atmosphere
Cumulonimbus Clouds
reaching high into the atmosphere
Lower levels of cumulonimbus clouds consist mostly of water droplets while at higher
elevations, where temperatures are well below 0 degrees Celsius, ice crystals
dominate. Under favorable atmospheric conditions, harmless fair weather cumulus
clouds can quickly develop into large cumulonimbus clouds associated with powerful
thunderstorms known as super cells.

11. produced by Kelvin-Helmholtz instability
Billow Clouds
produced by Kelvin-Helmholtz instability
Billow clouds are created from instability associated with air flows having marked
vertical shear and weak thermal stratification. The common name for this instability
is Kelvin-Helmholtz instability. These instabilities are often visualized as a row of
horizontal eddies aligned within this layer of vertical shear.

12. sagging pouch-like structures
Mammatus Clouds
sagging pouch-like structures
Sometimes very ominous in appearance, mammatus clouds are harmless and do not
mean that a tornado is about to form; a commonly held misconception. In fact,
mammatus are usually seen after the worst of a thunderstorm has passed.

13. Pileus Clouds
smooth capping clouds
Pileus (Latin for "skullcap") is a smooth cloud found attached to either a mountain
top or growing cumulus tower.

14. Cloud Type
Effects on Flight
cirrus
no significant icing; turbulence in dense, banded cirrus
cirrocumulus
supercooled water droplets = some turbulence and icing
cirrostratus
little if any icing; no turbulence; restricted visibility
altocumulus
small amounts of icing; some turbulence
altostratus
moderate amounts of icing; little turbulence; restricted sunlight
unstable air; rough turbulence with some icing
lenticular altocumulus
very strong turbulence
nimbostratus
very little turbulence; can pose serious icing problems if temperatures are near or below freezing
stratus
little or no turbulence; hazardous icing conditions if temperatures are near or below freezing. Fog on ground.
stratocumulus
some turbulence; possible icing at subfreezing temperatures; ceiling and visibility better than with low stratus clouds
cumulus
sunstable air will give some turbulence, but no significant icing
towering cumulus
strong turbulence,rain showers; clear icing above freezing level
cumulonimbus
unstable air; violent turbulence; strong possibility for icing
                   

15. CLOUD IDENTIFICATION TEST

16. Cirrus

17. Fair Weather Cumulus

18. Stratus

19. Nimbostratus
Stratus
Virga

21. Towering cumulus

22. Lenticulars

23. Fair-weather cumulus

24. Altocumulus

25. Cumulonimbus

26. Stratocumulus

27. Cumulonimbus

28. Mammantus

29. Mammantus

30. Moon
Altostratus
Scattered stratus

31. Cumulonimbus

32. Towering cumulus
Cirrostratus
Altocumulus

33. Roll cloud
Cumulonimbus

34. Altocirrus
Cirrus

35. Altostratus
Cumulus
Stratus

36. Which way is the wind blowing?
What time of day is it?
Evening

37. Cirrus
Fair-weather cumulus
Altostratus

38. Advection fog
Upslope fog
Is there a light wind?
Yes
Which way is it blowing?

39. Stratocumulus
Stratus

40. Cumulus

42. Stratocumulus

43. Thor

44. Stratus

45. Fair-weather cumulus
Tree

46. Stratocumulus

47. Stratus
Cumulus
Stratocumulus

48. Cirrocumulus
Stratus
Stratocumulus

49. Stratocumulus

50. Altocumulus and crazy pilot

51. Stratus
Towering cumulus
Romantic interlude

52. See the orthographic build-ups on the far side of the mountain?
Which way is the wind blowing?
What time of day is it?
Afternoon

53. Stratus

54. Cumulus
Bristlecone pine – lives longer than 2000 years.
This particular Bristlecone may have been living
during the life of Christ!

55. Cumulonimbus
Stratus
Towering cumulus
Altostratus

57. Fair-weather cumulus – looking up from the bottom

58. Fair-weather cumulus – looking down from the top

59. Altostratus
Stratus
Cumulus
Crab

60. Are these Pileus clouds?
Cumulonimbus
Cumulus

61. Cirrus

62. Cirrus

63. Fair-weather cumulus
Altostratus
Be careful! Low-flying military aircraft practice here!

65. Fair-weather cumulus

66. Stratocumulus

67. Altostratus
Cumulus

68. Cumulonimbus
Cold front
WARM AIR
Alien
COLD AIR
See the anvil top?
Altostratus
Which way is the storm moving?
Altocumulus

69. Cumulus
Cirrus
Cirrocumulus

70. Towering cumulus

71. Stratus
Cumulus

72. TV antenna
Altocumulus

73. Altocumulus
Cirrus

74. Stratus
Towering cumulus
The leading edge of a cold front. Aircraft avoid these things!

78. Cirrus

79. What direction is the wind blowing?