From Wikipedia, the free encyclopedia
High-altitude, very thin, generally uniform cloud
Cirrostratus cloud
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![](//upload.wikimedia.org/wikipedia/commons/thumb/3/36/Cirrostratus_with_mock_sun.jpg/220px-Cirrostratus_with_mock_sun.jpg) Cirrostratus nebulosus clouds being illuminated by the sun
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Abbreviation
| Cs
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Genus
| Cirrus- "
curl
" and
-stratus "
layered
"
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Species
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Variety
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Altitude
| 6,000 - 13,000 m
(20,000 - 43,000 ft)
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Classification
| Family A (High-level)
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Appearance
| Thin, transparent, high-altitude layer capable of producing a halo.
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Precipitation
| No, but usually signal the approach of a warm front. But rain in 24 hours
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Cirrostratus
is a high-altitude, very thin, generally uniform
stratiform
genus-type of
cloud
. It is made out of
ice
-crystals, which are pieces of frozen water. It is difficult to detect and it can make
halos
. These are made when the cloud takes the form of thin
cirrostratus nebulosus
.
[1]
The cloud has a fibrous texture with no halos if it is thicker
cirrostratus fibratus
. On the approach of a frontal system, the cirrostratus often begins as nebulous and turns to fibratus. If the cirrostratus begins as fragmented of clouds in the sky it often means the front is weak. Cirrostratus is usually located above 5.5 km (18,000 ft). Its presence indicates a large amount of
moisture
in the upper
troposphere
.
[2]
Clouds resembling cirrostratus occasionally form in polar regions of the lower stratosphere.
Polar stratospheric clouds
can take on this appearance when composed of tiny supercooled droplets of water or nitric acid.
[3]
Cirrostratus at night causing a moon halo
Cirrostratus clouds sometimes signal the approach 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
[4]
or as soon as 6?8 hours if the front is fast moving. If the cirrostratus is broken fibratus, it can mean that the front is weak and that stratus rather than nimbostratus will be the precipitating cloud (meaning drizzle or snow grains instead of moderate rain or snow).
Cumulus humilis
or
stratocumulus
clouds are often found below cirrostratus formations, due to the stable air associated with cirrostratus creating an
inversion
and restricting convection, causing cumuliform clouds to become flattened.
Contrails
also tend to spread out and can be visible for up to an hour in cirrostratus.
The phrase "milky sunshine" is often, as well as referring to
haze
or light
mist
, used to refer to the milky look of the sky when cirrostratus is present.
High cloud weather map symbols.
- Species: Cirrostratus
fibratus
(Cs fib) is a high fibrous sheet similar to cirrus but with less detached semi-merged filaments. It is reported in the SYNOP code as C
H
8 or as C
H
5 or 6 (depending on the amount of sky covered) if increasing in amount. If the high cloud covers the entire sky and takes on the form of a featureless veil, it is classified as cirrostratus of the species
nebulosus
(Cs neb)
[5]
and is coded C
H
7.
- Varieties: Cirrostratus species have no opacity-based varieties as they are always translucent. Two pattern-based varieties are sometimes seen with the species fibratus. These are the closely spaced
duplicatus
and wavy
undulatus
types similar to those seen with cirrus fibratus.
[6]
Pattern-based varieties are not commonly associated with the species nebulosus due to its lack of features.
- Supplementary features: Cirrostratus produces no precipitation or virga, and is not accompanied by any accessory clouds.
[7]
- Genitus mother clouds: Cirrostratus fibratus
cirrocumulogenitus
sometimes appears as the latter cloud flattens and loses some of its stratocumuliform structure. Cirrostratus fibratus
cumulonimbogenitus
may form if the cirriform top of a mature thundercloud spreads and flattens sufficiently to become a high stratiform cloud.
[8]
- Mutatus mother clouds: Cirrostratus fibratus
cirromutatus
or
cirrocumulomutatus
are the result of a complete transformation from cirrus and cirrocumulus genus types. Cirrostratus nebulosis
altostratomutatus
results when a high grey nebulous altostratus layer thins out into a whitish layer of featureless high cloud.
[8]
See also
[
edit
]
References
[
edit
]
- ^
World Meteorological Organization, ed. (1975).
Cirrostratus, International Cloud Atlas
. Vol. I. pp.
29?31
.
ISBN
92-63-10407-7
. Retrieved
26 August
2014
.
- ^
Ludlum, D. (1991). New York: Alfred A. Knopf.
ISBN
0-679-40851-7
.
- ^
World Meteorological Organization, ed. (2017).
"Nitric acid and water PSC, International Cloud Atlas"
. Retrieved
3 April
2019
.
- ^
Vekteris, Donna (2004).
Scholastic Atlas of Weather
. Scholastic Inc. p.
14
.
ISBN
0-439-41902-6
.
- ^
World Meteorological Organization
, ed. (1975).
Species, International Cloud Atlas
. Vol. I. pp.
17?20
.
ISBN
92-63-10407-7
. Retrieved
26 August
2014
.
- ^
World Meteorological Organization, ed. (1975).
Varieties, International Cloud Atlas
(PDF)
. pp. 20?22. Archived from
the original
(PDF)
on 25 July 2016
. Retrieved
26 August
2014
.
- ^
World Meteorological Organization
, ed. (1975).
Features, International Cloud Atlas
. Vol. I. pp.
22?24
.
ISBN
92-63-10407-7
. Retrieved
26 August
2014
.
- ^
a
b
World Meteorological Organization, ed. (1995).
"WMO cloud classifications"
(PDF)
. Retrieved
1 February
2012
.
External links
[
edit
]
Cloud
genera
and selected species, supplementary features, and other airborne
hydrometeors
-
WMO
Latin terminology except where indicated
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Mesospheric
| Extreme-level
80?85 km
| Noctilucent
(NLC)
Polar mesospheric clouds
|
- Noctilucent type I veils
- Noctilucent type II bands
- Noctilucent type III billows
- Noctilucent type IV whirls
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Stratospheric
| |
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Tropospheric
| High-level
3?18 km
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Medium-level
2?8 km
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Low-level
0?2 km
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Non-height
specific
| Varieties
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Supplementary features
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Mother clouds
and human-made clouds
|
- (Mother cloud)+genitus (e.g. cumulogenitus (cugen)
- (Mother cloud)+mutatus (e.g. cumulomutatus (cumut)
- Homogenitus (hogen)
- Homomutatus (homut)
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