Cloud altocumulus cloud has been given the Latin name "asperitas". The supplementary feature "cavum" is a circular fall-streak hole that occasionally forms in a thin layer of supercooled altocumulus or cirrocumulus. Fall streaks consisting of virga or wisps of cirrus are usually seen beneath the hole as ice crystals fall out to a lower altitude. This type of hole is usually larger than typical lacunosus holes. A "murus" feature is a cumulonimbus wall cloud with a lowering, rotating cloud base than can lead to the development of tornadoes. A "cauda" feature is a tail cloud that extends horizontally away from the
Altocumulus castellanus cloud 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. Castellanus clouds are evidence of mid-atmospheric instability and a high mid-altitude lapse rate. They may be a harbinger of heavy showers and thunderstorms and, if surface-based convection can connect to