Cloud types

Clouds are defined by their general appearance and level in the atmosphere.

	Cirrus clouds are curly or fibrous
	Stratus clouds are flat and/or layered
	Cumulus clouds are puffy and piled up.

Additionally, a prefix is frequently given to the cloud name to indicate what level of the atmosphere it is in.

Cirro is the prefix given to high clouds, those with bases above 20,000 feet.
Alto is the prefix given to mid-level clouds, those between 6,000 and 20,000 feet.
Nimbo added to the beginning, or nimbus added to the end of a cloud name means the cloud is producing precipiation.

The system is by no means uniform. There is no term for low clouds, and there are some odd joinings, such as stratocumulus, which is a cloud with two different shapes.

So here's how some cloud types stack up...

Cloud Type	Appearance	Altitude
Cumulonimbus	Thunderheads	Near ground to above 50,000 feet
Cirrostratus	Thin, wispy, above thunderheads	Above 18,000 feet
Cirrus	Thin, often with "mare's tail"	Above 18,000 feet
Cirrocumulus	Small puffy clouds	Above 18,000 feet
Altostratus	Thin, uniform, sometimes with "wide wale corduroy" appearance	6,000 - 20,000 feet
Altocumulus	Medium-sized puffy clouds	6,000 - 20,000 feet
Stratocumulus	Broad and flat on the bottom, puffy on top	Below 6,000 feet
Cumulus	Puffy clouds	Below 6,000 feet
Stratus	Uniform, thick to thin layered clouds	Below 6,000 feet

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