Altostratus (As) and Altocumulus (Ac)
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| Visible image | Infrared image | Water Vapour image | |
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 Altostratus: smooth, no texture; white (grey if
thin and with no underlying cloud) Altocumulus: minimal texture; white. |
Little, if any, texture; grey (mid to light) |
White if thick, grey if less dense |
Altostratus and Altocumulus clouds are difficult to differentiate on satellite imagery
due to their association with each other and within synoptic systems. For this reason the two cloud types are often referred to together as AcAs. Often the cloud is covered with Cirrostratus, in which case the tops are usually
smooth and bright. On the Visible imagery when there are cloud layers at different heights
(e.g. Cirrostratus over AcAs along a frontal cloud band) a shadow line may enable the separate
cloud formations to be resolved. Edges tend to be well defined. Mountain ranges may induce gravity wave patterns in the cloud shield.
| View examples of Altostratus/Altocumulus clouds on the imagery. |
