Cloud Classification


General description

Thin, white patch, sheet or layer of cloud without shading, composed of very small elements in the form of grains, ripples, merged or separate, and more or less regularly arranged.

Most of the elements have an apparent width of less than one degree (when observed at an angle greater than 30 degrees above the horizon). This is about the width of the little finger at arm's length.

Common subdivisions

A common species is Cirrocumulus stratiformis, showing a relatively extensive sheet or layer, sometimes with gaps, breaches or rifts.

Other species include lenticularis, castellanus and floccus.

Distinguishing Cc from other genera

Cirrocumulus differs from Altocumulus in that most of its elements have an apparent width of less than one degree, and it is without shading. A cloud should not be called Cirrocumulus if it consists of a patch of incompletely developed small elements, such as when observed on the edges of a patch of Altocumulus, or if present in separate patches at the same level as Altocumulus.

Cirrocumulus differs from Cirrus and Cirrostratus in that it appears rippled or grainy; it may include fibrous or smooth portions, but these do not constitute its greater part. In middle or high latitudes, Cirrocumulus is usually associated with other cirriform clouds; less often in low latitude regions. In synoptic observations, Cirrocumulus must dominate the cirriform clouds for it to be reported. This practice would also be considered reasonable for aviation observations.

Associated precipitation

Cirrocumulus is not associated with any precipitation.

cirrocumulus stratiformis
Cirrocumulus stratiformis
cirrocumulus stratiformis
Cirrocumulus stratiformis (Photo: NOAA)
Cirrocumulus with other cirroform cloud