Cloud Nomenclature

The ten main cloud types are named on the basis of their appearance and height. Below is a table of the latin roots used to distinguish clouds based on appearance.

Root	Latin meaning	Description
Stratus	"layer"	Flat, layered cloud
Cumulus	"heap"	Puffy cloud
Cirrus	"curl of hair"	Wispy cloud

This basic system was expanded upon in the late nineteenth century to produce the current classification system, which contains ten main cloud types (the ones described on this page). In the modern nomenclature, the prefix "cirro-" is added for upper-level clouds, and the prefix "alto-" for mid-level clouds. The Latin root "nimbus" is used to designate rain-producing clouds.

A number of descriptive terms may be applied to the more general terms used for the main cloud types. Some of the more common ones are listed below.

Lenticularis - "lens-shaped" clouds, usually of the type altocumulus. These are almost always found over mountainous regions, and form when moist air follows a wave pattern over the topography, condensing as it reaches the crest of the wave.

Pileus - cap-shaped formation usually found immediately above a cumulus congestus or cumulonimbus cloud as it develops vertically.

Mammatus - small, "bag-like" formations that appear below a parent cloud (most commonly cumulonimbus, but can occur under various cloud types). Form as a result of air sinking below the main cloud level that remains cool enough to continue condensation.

Fractus - "fractured" or ragged-looking cumulus or stratus clouds

Humilis - type of cumulus cloud with minimal vertical growth and generally flat bases; "fair-weather" cumulus