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.
Cloud
The genitus and mutatus categories have been expanded to include certain types that do not originate from pre-existing clouds. The term "flammagenitus" (Latin for 'fire-made') applies to cumulus congestus or cumulonimbus that are formed by large scale fires or volcanic eruptions. Smaller low-level "pyrocumulus" or "fumulus" clouds formed by contained industrial activity are now classified as cumulus "homogenitus" (Latin for 'man-made'). Contrails formed from the exhaust of aircraft flying in the upper level of the troposphere can persist and spread into formations resembling any of the high cloud genus-types and are now officially designated as cirrus, cirrostratus, or cirrocumulus homogenitus. If a homogenitus cloud of one genus changes to another genus type, it is then termed a "homomutatus" cloud. Stratus cataractagenitus (Latin for 'cataract-made') are generated by the spray from waterfalls. "Silvagenitus" (Latin for 'forest-made') is a stratus cloud that forms as water vapor is added to the air above a forest canopy.