C_L4 Sc from spreading out of Cu

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Gallery
© R.K. Pilsbury	© G.A. Watt
© S.G. Cornford	© R.A.R. Tricker
© R.K. Pilsbury	© R.K. Pilsbury
© R.K. Pilsbury	© R.K. Pilsbury

This type of stratocumulus most often forms when the upper part of cumulus clouds, that have been gaining height but are no longer able to do so, begin to spread out horizontally. The cumulus generally widens towards the spreading out level (top photographs). Sometimes the cumulus growth is resumed, at least in some places, above the stratocumulus. Ragged mamma often appear on the underside of the stratocumulus (2nd row left). However, the individual mamma elements are short-lived and do not appear as prominent as those shown at 2nd row right (normally associated with Cb).

Another form of C_L4 often occurs in the evening when the sun's heating decreases and consequently cumulus clouds flatten and assume the appearance of patches of stratocumulus. This is depicted in the bottom group of four photographs, taken over a 20 minute period. It should be noted that Cirrus and cirrostratus also appear in these photographs.

Classification
Description: Stratocumulus formed by the spreading out of Cumulus.	Designation: CL=4 (C6)
	Latin name: Stratocumulus cumulogenitus (Sc cugen).

Related pages: Cloud classification | C_L guide | C_M guide | C_H guide | Cloud index