Cirrus Clouds (High Cloud Group)
photographer: Walter J. Pilsak.
photographer: Stefan Bauer
Cirrus clouds are made entirely of ice. They appear long, thin, and are fine and feathery. They are called "mare's tails" because they look like a horse's tail.
Cirrus clouds are usually white and can be the first sign of an approaching warm front that may arrive in a few days bringing prolonged precipitation.