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Altocumulus Clouds - Windows to the Universe

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This is a photograph of altocumulus clouds.
Click on image for full size
Courtesy of UCAR Digital Image Library

Altocumulus

Altocumulus clouds (weather symbol - Ac), are made primarily of liquid water and have a thickness of 1 km. They are part of the Middle Cloud group (2000-7000m up). They are grayish-white with one part of the cloud darker than the other. Altocumulus clouds usually form in groups.

You can distinguish an altocumulus cloud from a stratocumulus cloud by pointing your hand toward the cloud. If the cloud is about the size of your thumbnail, then it is altocumulus.

Altocumulus clouds in view on a warm humid morning indicate thunderstorms by late afternoon.


Last modified September 25, 2007 by Becca Hatheway.

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Altocumulus

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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support! NASA AGU AGI NSF