CIRROSTRATUS over Low Clouds A very thin and uniform layer of cirrostratus cloud over low clouds in Ohio. The low clouds are on the edge between cumulus and stratocumulus. Photo by Carolyn Green in Ohio, 2000.
CIRROSTRATUS Haze This photo, taken near sunset in Colorado by Kevin Larman, show a very thin and very uniform cirrostratus cloud with streaks of thicker cirrus (perhaps old contrails?). Near the horizon some opaque low clouds are visible.
Cirrostratus clouds are thin, sheetlike high clouds that often cover the entire sky. They are so thin that the sun and moon can be seen through them. Cirrostratus clouds usually come 12-24 hours before a rain or snow storm.
Cirrostratus clouds are thin, generally uniform clouds, composed of ice-crystals. They are difficult to detect and if capable of forming halos the cloud takes the form of thin cirrostratus nebulosus. Its presence indicates a large amount of moisture in the upper atmosphere. Cirrostratus clouds sometimes signal the beginning of a warm front if they form after cirrus and spread from one area across the sky and thus may be signs that precipitation might follow in the next 12 to 24 hours.
The "halo cloud" was just an optical illusion caused by sunlight hitting a cloud at just the right angle. The cloud's round shape is likely what is known as a hole-punch cloud. These clouds occur within cirrostratus clouds, which are often composed of ice crystals and drops of water that are below freezing temperature but still in liquid form. When cirrostratus clouds are disturbed by planes or strong winds, the droplets can freeze instantly or evaporate, the latter of which will form the…