Principles of cloud classification

Clouds change their shape according to processes in the atmosphere and have many individual shapes but only a very few basic forms. The three principle families of clouds have the Latin names cirrus (meaning "fibre" or "hair"), cumulus ("heap or "pile"), and Stratus ("layer" or "sheet"). Luke Howard, an amateur meteorologist, first classified the various clouds based on their appearance in 1802.

The World Meteorological Organization (WMO) cloud classification scheme uses genera, species and varieties in its International Cloud Atlas. A cloud may be described in terms of genera, species and variety e.g. Altocumulus stratiformis duplicatus (a stratiform species of altocumulus that occurs in two or more layers). Clouds sometimes have supplementary features or accessory clouds.