How to Identify Clouds

Understanding clouds and their formation is not as difficult as it may seem at first. Anyone can learn how to do an amateur weather prediction in their area from observing clouds and noting details such as whether they are moving, or if they are changing altitude or color.

Clouds are formed from water that evaporates into the air from any water surface, whether ocean, river or lake. Plants also give off vapors of moisture that rise into the air to assist in cloud formation. This moisture is constantly rising, although we can't see it occurring.

There are three basic classifications of clouds by altitude: low, middle and high altitude.

Low altitude clouds

Low clouds are located from the ground to a height of 7,000 feet. They are cumulonimbus, cumulus, nimbostratus or stratus. Cumulonimbus clouds are often called thunderheads, appearing with a stormy-appearing, dark ragged base and a broad, anvil-shaped top. They appear to be "piled up."

Cumulus clouds are seen in generally fair weather. They look more puffy or fleecy to the viewer.

Nimbostratus is the classification for clouds which are stretched out over the sky, layered and dark. They will be producing steady precipitation of either snow, rain, or hail.

Stratus clouds are very low, producing what we commonly called fog and sometimes a drizzle.

Middle altitude clouds

Middle altitude clouds are identified from 7,000 up to 20,000 feet. These types are either altostratus or altocumulus clouds.

Altostratus clouds often produce a light rain, and they look like stripes in the sky somewhat the appearance of a frosty glass.

Altocumulus clouds look puffy but show up in parallel bands. Normally they do not produce rain but indicate that rain is likely coming.

High altitude clouds

High altitude clouds are those that appear above 20,000 feet. They are cirrocumulus or cirrus, and both of them mean there is little moisture in the air and fair weather is about. Both types are thin, but their appearance is a little different.

Cirrus clouds are wispy and extended, the source of their moniker "mare's tails." Cirrocumulus clouds look more stacked up and curly.

Cloud motion

The prime difficulty with reading clouds to forecast the weather lies in keeping track of how quickly they can change altitude or move across the sky. Many times we can see the clouds slowly "moving out" or changing to a different type, thus we can tell whether fair or stormy weather is due.

An individual usually needs some experience observing clouds carefully in their locality in order to tell how fast which types of clouds change from fair weather clouds to clouds which indicate an approaching storm. This can take place much more quickly in some areas than others, and according to which season is being observed.

Cloud watching can provide a fascinating activity for adults and children alike. Try spending some idle weekends closely observing the sky in your area and see what you can learn about your local clouds and weather patterns.

Sources:

"Joy of Nature", p. Reader's Digest, 1977

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