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
Arcus cloud vortices along the edge, with twisting masses of scud that may reach to the ground or be accompanied by rising dust. A very low shelf cloud accompanied by these signs is the best indicator that a potentially violent wind squall is approaching. An extreme example of this phenomenon looks almost like a tornado and is known as a gustnado. A roll cloud ("Cloud Atlas" name " volutus") is a low, horizontal, tube-shaped, and relatively rare type of arcus cloud. They differ from shelf clouds by being completely detached from other cloud features. Roll clouds usually appear to be "rolling" about