WordNet
n. a wispy white cloud (usually of fine ice crystals) at a high altitude (4 to 8 miles) [syn: cirrus]
Wikipedia
Cirrus ( cloud classification symbol: Ci) is a genus of atmospheric cloud generally characterized by thin, wispy strands, giving the type its name from the Latin word cirrus, meaning a ringlet or curling lock of hair. The strands of cloud sometimes appear in tufts of a distinctive form referred to by the common name of "mares' tails".
On planet Earth, cirrus generally appears white or light gray in color. It forms when water vapor undergoes deposition at altitudes above in temperate regions and above in tropical regions. It also forms from the outflow of tropical cyclones or the anvils of cumulonimbus cloud. Since cirrus clouds arrive in advance of the frontal system or tropical cyclone, it indicates that weather conditions may soon deteriorate. While it indicates the arrival of precipitation (rain), cirrus clouds only produce fall streaks (falling ice crystals that evaporate before landing on the ground).
Jet stream-powered cirrus can grow long enough to stretch across continents while remaining only a few kilometers deep. When visible light interacts with the ice crystals in cirrus cloud, it produces optical phenomena such as sun dogs and haloes. Cirrus is known to raise the temperature of the air beneath the main cloud layer by an average of 10 °C (18 °F). When the individual filaments become so extensive that they are virtually indistinguishable from one another, they form a sheet of high cloud called cirrostratus. Convection at high altitudes can produce another high-based genus called cirrocumulus, a pattern of small cloud tufts that contain droplets of supercooled water.
Cirrus clouds form on other planets, including Mars, Jupiter, Saturn, Uranus, and possibly Neptune. They have even been seen on Titan, one of Saturn's moons. Some of these extraterrestrial cirrus clouds are composed of ammonia or methane ice rather than water ice. The term cirrus is also used for certain interstellar clouds composed of sub- micrometer-sized dust grains.
Usage examples of "cirrus cloud".
A layer of thin cirrus cloud coated the eastern sky, stained red by the light of the aged sun.
Sol was a point of light, low on Lvov's unfolding horizon, wreathed in the complex strata of a cirrus cloud.
The end came in a gloriously sharp double peak crowned with a few flecks of cirrus cloud, and all they could think of in camp that night was this splendid twin-peaked mountain, which even in such a lofty country looked like a giant among pigmies.
One is brilliant, a genius who floats above her colleagues like a cirrus cloud, the other is merely a plodder: dogged, determined, competent.
Looking down on an enlarged image of the hurricane, Heidi never ceased to be impressed with the evil beauty of the thick, spiraling white clouds called the central dense overcast, the cirrus cloud shield that evolves from the thunderstorms in the surrounding walls of the eye.
There were wisps of cirrus cloud, high and peaceful, still touched with the red of sunset.
Shasa throttled back the Rolls Royce engines and the Mosquito sank down through the ribbons of scattered cirrus cloud, and the endless golden plains of the high African shield came up to meet her.
At night the sky beyond our windows was generally clear, with only a light frosting of cirrus cloud high in the depleted, lethal atmosphere.
High in the sky, a long horse's-tail of cirrus cloud was curled by the wind.
Beyond dimly discerned low prow and stern and mainyard top, vision was utterly blotted out by a fog of tiniest ice crystals, like cirrus cloud come down from Stardock heights, through which the light of an unseen gibbous moon, still almost full swollen, seeped out dark pearl gray.
At first he thought that it might have been a shadow cast by the moon as the fluffy white cirrus cloud floated by.