High clouds that are formed entirely from ice crystals. They appear delicate and wispy and can reach a height of 35,000 feet (10,700 meters). Other types of cirrus clouds include cirrostratus and cirrocumulus. Cirrostratus is a thin sheet of cloud that often causes a halo to appear around the sun or moon. Cirrocumulus look like many small tufts of cotton; however, these clouds rarely form. [Journal of Applied Meteorology. v 31, page 370, 1991.] [Journal of the Atmospheric Sciences. v 46, page 2293, 1989.
High altitude cloud composed of ice crystals. The appearance of these clouds is white feather like patches, filaments or thin bands. Found in an altitude range from 5,000 to 18,000 meters.