Cirrus cloud
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. Such a cloud can form at any altitude between above sea level. The strands of cloud sometimes appear in tufts of a distinctive form referred to by the common name of "mares' tails".

From the surface of Earth, cirrus clouds typically appear white, or a light grey, in color; they form when water vapor undergoes deposition at altitudes above , in temperate regions, and above in tropical ones. They also form from the outflow of tropical cyclones, and from the anvils of cumulonimbus clouds. They also arrive in advance of those storms' associated frontal systems, likely a deterioration in weather conditions. Though indicating the arrival of precipitation, these clouds produce, themselves, at most fall streaks, whose ice crystals evaporate in warmer and drier air, without reaching ground level.

Jet stream-powered cirrus can grow long enough to stretch across continents, while remaining only a few kilometers deep. Interaction of visible light with the ice crystals in them produces, below, optical phenomena such as sun dogs and halos. Cirrus is known to raise the temperature (due the heat released as water vapor freezes) of the air beneath the main cloud layer, by an average of 10 °C (18 °F), When the individual filaments become so extensive as to be virtually indistinguishable, one from another, they form a sheet of high cloud called cirrostratus. Convection at high altitudes can produce another high-based genus of cloud, cirrocumulus, with a pattern of small cloud tufts containing droplets of supercooled water. Some polar stratospheric clouds can resemble cirrus, and noctilucent clouds typically become structured in ways similar to those of cirrus.

Cirrus clouds also form in the atmospheres of other planets, including Mars, Jupiter, Saturn, Uranus, and Neptune, and have been seen even on Titan, one of Saturn's larger moons. Some of these extraterrestrial cirrus clouds are composed of ammonia or ices of methane, much as with terrestrial water ice. (The term "cirrus" also applies to certain interstellar clouds, composed of sub-micrometer-sized grains of dust.
Q3281195
cloud classification
UNK
Q8074
cloud
Concept
Q397
Latin
Concept
Q190200
altitude
Concept
Q125465
sea level
Concept
Q190120
water vapor
Concept
Q871279
deposition
Concept
Q167466
temperate region
Concept
Q42530
tropical
LOC
Q3308838
outflow
UNK
Q8092
tropical cyclone
Concept
Q1358304
anvils
Concept
Q182311
cumulonimbus clouds
Concept
Q189796
frontal system
Concept
Q25257
precipitation
Concept
Q215631
fall streak
Concept
Q1325808
ice crystal
Concept
Q202325
Jet stream
Concept
Q52948
Interaction
Concept
Q14506045
optical phenomena
Concept
Q208589
sun dog
Concept
Q186310
halos
Concept
Q108000
freezes
Concept
Q201564
cirrostratus
Concept
Q160329
Convection
Concept
Q34740
genus
Concept
Q40748
cirrocumulus
Concept
Q213659
supercooled
Concept
Q216417
polar stratospheric
Concept
Q192794
noctilucent
Concept
Q634
planet
Concept
Q111
Mars
CEL
Q319
Jupiter
CEL
Q193
Saturn
CEL
Q324
Uranus
CEL
Q332
Neptune
CEL
Q2565
Titan
DIS
Q4087
ammonia
Concept
Q389036
ices of methane
Concept
Q2
terrestrial
CEL
Q1054444
interstellar cloud
Concept
Q175821
micrometer
Concept
Q165632
dust
Concept
Q185638
Cirrus cloud
Concept
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