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APOD

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

See Explanation. Clicking on the picture will download the highest resolution version available.

Anvil Cloud Over Sicily

Explanation: The cloud poses no danger to the building. Appearing to float above a remote monastery in Sicily , Italy , the anvil cloud 's shape shows several classic cloud features. The cloud itself is composed of millions of very small droplets of water and ice . The dramatically flat cloud bottom is caused by temperature falling in the lower atmosphere -- above a specific height water-saturated air is forced to condense out water droplets. The shape of the cloud middle is caused by the water-droplet-laden column of air being blown both upward and to one side. The anvil shape at the cloud top is likely caused by the upward air column reaching a stable atmospheric layer, likely the stratosphere , where horizontally moving air fans out the top of the cloud. The cumulonimbus cloud was captured out the front door of a house last year.

Date February 18, 2004
Credit Credit & Copyright: Christina Carlton
Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
A service of: ASD at NASA / GSFC,
NASA Science Activation & Michigan Tech. U.