Cirrus (cloud classification symbol: Ci) is a genus of high cloud made of ice crystals. Cirrus clouds typically appear delicate and wispy with white strands. Cirrus are usually formed when warm, dry air rises, causing water vapor deposition onto rocky or metallic dust particles at high altitudes. Globally, they form anywhere between 4,000 and 20,000 meters (13,000 and 66,000 feet) above sea level, with the higher elevations usually in the tropics and the lower elevations in more polar regions.
Cirrus clouds can form from the tops of thunderstorms and tropical cyclones and sometimes predict the arrival of rain or storms. Although they are a sign that rain and maybe storms are on the way, cirrus themselves drop no more than falling streaks of ice crystals. These crystals dissipate, melt, and evaporate as they fall through warmer and drier air and never reach ground. Cirrus clouds warm the earth, potentially contributing to climate change. A warming earth will likely produce more cirrus clouds, potentially resulting in a self-reinforcing loop.
Optical phenomena, such as sun dogs and halos, can be produced by light interacting with ice crystals in cirrus clouds. There are two other high-level cirrus-like clouds called cirrostratus and cirrocumulus. Cirrostratus looks like a sheet of cloud, whereas cirrocumulus looks like a pattern of small cloud tufts. Unlike cirrus and cirrostratus, cirrocumulus clouds contain droplets of supercooled (below freezing point) water.
Cirrus clouds form in the atmospheres of Mars, Jupiter, Saturn, Uranus, and Neptune; and on Titan, one of Saturn's larger moons. Some of these extraterrestrial cirrus clouds are made of ammonia or methane ice, much like water ice in cirrus on Earth. Some interstellar clouds, made of grains of dust smaller than a thousandth of a millimeter, are also called cirrus.
Cirrus (cloud classification symbol: Ci) is a genus of high cloud made of ice crystals. Cirrusclouds typically appear delicate and wispy with white strands...
Cirrus uncinus is a type of cirruscloud. The name cirrus uncinus is derived from Latin, meaning "curly hooks". Also known as mares' tails, these clouds...
The list of cloud types groups all cloud genera as high (cirro-, cirrus), middle (alto-), multi-level (nimbo-, cumulo-, cumulus), and low (strato-, stratus)...
Cirruscloud thinning (CCT) is a proposed form of climate engineering. Cirrusclouds are high cold ice that, like other clouds, both reflect sunlight and...
altocumulus, cirrocumulus, lenticular, and cirrusclouds. They sometimes appear as bands parallel to the edge of the clouds. Iridescence is also seen in the much...
Cirrus spissatus or also called Cirrus densus and Cirrus nothus clouds are the highest of the main cloud genera, and may sometimes even occur in the lower...
Cirrus intortus is a variety of cirruscloud. The name cirrus intortus is derived from Latin, meaning "twisted, wound". The variety of intortus clouds...
cirrus which are designated cirrus homogenitus. If a cirrus homogenitus cloud changes fully to any of the high-level genera, they are termed cirrus,...
the three main genus types of high-altitude tropospheric clouds, the other two being cirrus and cirrostratus. They usually occur at an altitude of 5 to...
Cirrus castellanus or Cirrus castellatus is a species of cirruscloud. Its name comes from the word castellanus, which means of a fort, of a castle in...
Cirrus fibratus or also called Cirrus filosus is a species of cirruscloud. The name cirrus fibratus is derived from Latin, meaning "fibrous". These clouds...
high-level cloud, cirrocumulus, is a stratocumuliform cloud of limited convection. The other clouds in this level are cirrus and cirrostratus. High clouds form...
water or nitric acid. Cirrostratus clouds sometimes signal the approach of a warm front if they form after cirrus and spread from one area across the...
animal Cirrus (botany), a tendril Infrared cirrus, in astronomy, filamentary structures seen in infrared light Cirruscloud, a type of cloudCirrus aero...
spread to be several miles wide, eventually resembling natural cirrus or altocumulus clouds. Persistent contrails are of particular interest to scientists...
large, and higher when it is low, such that subvisible cirrusclouds are counted). Average cloud cover is around 72% over the oceans, with low seasonal...
Cirrus vertebratus is a type of cirruscloud. The name cirrus vertebratus is derived from Latin, meaning "jointed, articulated, vertebrated". Like cirrus...
thin clouds (such as cirrusclouds) do not generate any precipitation at the surface of the Earth. For a synthetic discussion of the impact of clouds on...
combustion. These clouds are commonly known as condensation trails (contrails), and are initially lineal cirrusclouds that could be called Cirrus homogenitus...
reflectivity of the Earth's surface to deflect solar radiation back into space Cirruscloud thinning (CCT), which is strictly not SRM but shares many of characteristics...
anvil clouds and also severe thunderstorms. They often extend from the base of a cumulonimbus cloud, but may also be found under altostratus, and cirrus clouds...
of which can increase cirruscloud formation – cloud cover may have increased by up to 0.2% since the birth of aviation. Clouds can have both a cooling...
in high altitude clouds such as cirrus. Thicker clouds have a higher albedo than thinner ones. In fact thick clouds and thin clouds will occasionally...
forcing is estimated at 1.3–1.4 that of CO2 alone, excluding induced cirruscloud with a very low level of scientific understanding. In 2018, global commercial...
considered a "beautiful natural phenomenon". Noctilucent clouds may be confused with cirrusclouds, but appear sharper under magnification. Those caused...
ice crystals suspended in the atmosphere, typically in actual cirrus or cirrostratus clouds. In its full form, the arc has the appearance of a large, brightly...
is highly unstable, cumulonimbus clouds producing thunderstorms commonly form along the front. Anvil cirrusclouds may spread a considerable distance...
Altostratus clouds are the only cloud genus besides cirrusclouds to exhibit a net global heating effect on Earth and its atmosphere; however, cirrus have a...
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