C_M9 Altocumulus of a chaotic sky

Click the small image for full size version.

Gallery
© C.S. Broomfield
© C.S. Broomfield
© R.K. Pilsbury

Altocumulus of a chaotic sky generally occurs at several levels. The sky is characterised by its heavy, stagnant appearance. You can expect to see broken cloud sheets of poorly defined cloud types, from the relatively low, thick altocumulus to the relatively high, thin altostratus. There is generally a mixture of low level and high level clouds also present in this type of sky.

In the top photograph the estimated base of the lowest cloud is 7,000 ft. There are confused higher layers up to the sheet of altostratus at 15,000 ft. A prominent turret of altocumulus castellanus can be seen in the centre of the photograph.

In the middle photograph ragged altocumulus and altostratus can be seen in several ill-defined layers, the lowest appearing grey in the light of the setting sun. The layers range in height from about 8,000 to 18,000 ft. It may be possible to see virga trailing beneath some of the clouds.

The bottom picture shows poorly defined patches of altocumulus and stratocumulus beneath extensive layers of altostratus and altocumulus.

Classification
Description: Altocumulus of a chaotic sky, generally at several levels.	Designation: CM=9 (C3)
	Latin name: Altocumulus duplicatus (Ac du).

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