Altostratus cloud

Altostratus cloud
Altostratus cloud
Abbreviation	As
Symbol
Genus	Alto- (High) -stratus (layered)
Altitude	2,400-6,100 m (8,000-20,000 ft)
Appearance	Sheet or layer, can usually see the sun through it
Precipitation cloud?	Showers possible in thickened clouds. Classification is changed to nimbostratus if rain becomes persistent.[1]
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Altostratus is a cloud belonging to a class characterized by a generally uniform gray sheet or layer, lighter in color than nimbostratus and darker than cirrostratus. The sun can be seen shining through them, and they frequently cover the whole sky. They are similar to lower altitude stratus clouds.

Altostratus is caused by a large air mass that is lifted then condensed, usually by an incoming frontal system and can be found over widespread areas. Altostratus clouds are potentially dangerous, because they can cause ice accretion on aircraft. Their altitude is from 8,000-20,000 feet (2,400-6,100 m). They are made from ice crystals.

Altostratus clouds can produce very light precipitation. However, the precipitation may be virga, especially in dry places. They are also at a medium altitude, but they can sometimes bring the altitude lower to produce rain and/or snow due to the weight of the cloud. Once the cloud seems to be lower, the sun can no longer be seen.

References

External links

Wikimedia Commons has media related to: Altostratus clouds

• Clouds-Online.com Cloud Atlas with many photos and description of the different cloud genus
• National Science Digital Library - Altostratus

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