List of cloud types
The list of cloud types groups the tropospheric types as "high" (cirrus, cirrocumulus, cirrostratus), "middle" (altocumulus, altostratus), "multi-level" (nimbostratus, cumulus, cumulonimbus), and "low" (stratocumulus, stratus) according to the altitude level or levels at which each cloud is normally found. Small cumulus are commonly grouped with the low clouds because they do not show significant vertical extent. Of the multi-level genus-types, those with the greatest convective activity are often grouped separately as "towering vertical". The genus types all have Latin names.
Altocumulus castellanus cloud
In meteorology, Altocumulus Castellanus (ACCAS) is a cloud type 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). They are very similar to cumulus congestus clouds, but at a higher level and with the cloud heaps joined at the base.