Altocumulus castellanus cloud

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Altocumulus castellanus
Altocumulus castellanus clouds
Abbreviation	Ac, ACCAS
Genus	Altocumulus (high, heaped)
Species	castellanus (castle)
Altitude	2,000 - 6,000 m (6,500 - 20,000 ft)
Classification	Family B (Medium-level)
Precipitation Cloud?	No, but could signify later precip.
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Altocumulus castellanus (ACCAS) is named for its tower-like projections that billow upwards from the base of the cloud. The base of the cloud can form as low as 2,000 metres (6,500 feet), or as high as 6,000 metres (20,000 feet).

Castellanus clouds are evidence of mid-atmospheric instability and a high mid-altitude lapse rate. They may be a harbinger of bad weather and, if surface-based convection can connect to the mid-tropospheric unstable layer, continued development of castellanus clouds can produce cumulonimbus clouds and thunderstorms.

Altocumulus Castellanus clouds can indicate rough turbulence for aircraft.

The appearance of Altocumulus Castellanus on a sunny morning announce with high probability the formation of thunderstorms in the afternoon.

[edit] External links

• Altocumulus Castellanus (Source: Australiasevereweather.com)

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