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
Cloud at which the air becomes saturated. The main mechanism behind this process is adiabatic cooling. As the air is cooled to its dew point and becomes saturated, water vapor normally condenses to form cloud drops. This condensation normally occurs on cloud condensation nuclei such as salt or dust particles that are small enough to be held aloft by normal circulation of the air. Frontal and cyclonic lift occur when stable air is forced aloft at weather fronts and around centers of low pressure by a process called convergence. Warm fronts associated with extratropical cyclones tend to generate mostly cirriform and