CIRROSTRATUS
A cirriform cloud that develops from cirrus spreading out into a thin layer, creating a flat sheetlike appearance. It can give the sky a slightly milky or veiled look. When viewed from the surface of the earth, these ice crystals can create a halo effect around the sun or moon. This cloud is a good precursor of precipitation, indicating it may occur within 12 to 24 hours.
A layer of high clouds composed of ice crystals. Cirrostratus are usually very thin and appear as a white fibrous cloud layer. The layer may be so thin that it may only be detected by the presence of a halo around the Sun. [See also stratus.]
