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 cloud
Altocumulus (From Latin "Altus", "high", "cumulus", "heaped") is a middle-altitude cloud genus that belongs mainly to the "stratocumuliform" physical category characterized by globular masses or rolls in layers or patches, the individual elements being larger and darker than those of cirrocumulus and smaller than those of stratocumulus. However, if the layers become tufted in appearance due to increased airmass instability, then the altocumulus clouds become more purely "cumuliform" in structure. Like other cumuliform and stratocumuliform clouds, altocumulus signifies convection. A sheet of partially conjoined altocumulus perlucidus is sometimes found preceding a weakening warm front, where the altostratus is starting to fragment, resulting in patches of altocumulus perlucidus between the areas of altostratus. Altocumulus is also commonly found between the warm and cold fronts in a depression, although this is often hidden by lower clouds.