Cirrostratus cloud
Encyclopedia
Cirrostratus icon cloud
s are thin, generally uniform clouds, composed of ice
-crystals. They are difficult to detect and if capable of forming halo
s the cloud takes the form of thin cirrostratus nebulosus
. The cloud has a fibrous texture with no haloes if it is thicker cirrostratus fibratus
. On the approach of a frontal system, the cirrostratus often begins as nebulosus and turns to fibratus. If the cirrostratus begins as fragmented fibratus 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 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 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 rain cloud (meaning drizzle instead of moderate rain). Cumulus humilis or stratocumulus clouds are often found below cirrostratus formations, this being due to the stable air associated with cirrostratus creating an inversion and restricting convection, causing cumuloform clouds to become flattened. Contrails also tend to spread out and can be visible for up to an hour in cirrostratus.
The phrase 'hazy 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.
Cloud
A cloud is a visible mass of liquid droplets or frozen crystals made of water and/or various chemicals suspended in the atmosphere above the surface of a planetary body. They are also known as aerosols. Clouds in Earth's atmosphere are studied in the cloud physics branch of meteorology...
s are thin, generally uniform clouds, composed of ice
Ice
Ice is water frozen into the solid state. Usually ice is the phase known as ice Ih, which is the most abundant of the varying solid phases on the Earth's surface. It can appear transparent or opaque bluish-white color, depending on the presence of impurities or air inclusions...
-crystals. They are difficult to detect and if capable of forming halo
Halo (optical phenomenon)
A halo from Greek ἅλως; also known as a nimbus, icebow or gloriole) is an optical phenomenon produced by ice crystals creating colored or white arcs and spots in the sky. Many are near the sun or moon but others are elsewhere and even in the opposite part of the sky...
s the cloud takes the form of thin cirrostratus nebulosus
Cirrostratus nebulosus
Cirrostratus nebulosus is a type of cirrostratus cloud. The name cirrostratus nebulosus is derived from Latin, meaning "full of vapor, foggy, cloudy, dark"...
. The cloud has a fibrous texture with no haloes if it is thicker cirrostratus fibratus
Cirrostratus fibratus
Cirrostratus fibratus is a type of cirrostratus cloud. The name cirrostratus fibratus is derived from Latin, meaning "fibrous". Cirrostratus fibratus is one of the two most common forms that cirrostratus often takes, with the other being cirrostratus nebulosus. They are formed from strong,...
. On the approach of a frontal system, the cirrostratus often begins as nebulosus and turns to fibratus. If the cirrostratus begins as fragmented fibratus 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
Moisture
Humidity is the amount of moisture the air can hold before it rains. Moisture refers to the presence of a liquid, especially water, often in trace amounts...
in the upper atmosphere
Atmosphere
An atmosphere is a layer of gases that may surround a material body of sufficient mass, and that is held in place by the gravity of the body. An atmosphere may be retained for a longer duration, if the gravity is high and the atmosphere's temperature is low...
.
Cirrostratus clouds sometimes signal the beginning of a warm front
Warm front
A warm front is a density discontinuity located at the leading edge of a homogeneous warm air mass, and is typically located on the equator-facing edge of an isotherm gradient...
if they form after cirrus and spread from one area across the sky and thus may be signs that precipitation
Precipitation (meteorology)
In meteorology, precipitation In meteorology, precipitation In meteorology, precipitation (also known as one of the classes of hydrometeors, which are atmospheric water phenomena is any product of the condensation of atmospheric water vapor that falls under gravity. The main forms of precipitation...
might follow in the next 12 to 24 hours 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 rain cloud (meaning drizzle instead of moderate rain). Cumulus humilis or stratocumulus clouds are often found below cirrostratus formations, this being due to the stable air associated with cirrostratus creating an inversion and restricting convection, causing cumuloform clouds to become flattened. Contrails also tend to spread out and can be visible for up to an hour in cirrostratus.
The phrase 'hazy sunshine' is often, as well as referring to haze
Haze
Haze is traditionally an atmospheric phenomenon where dust, smoke and other dry particles obscure the clarity of the sky. The World Meteorological Organization manual of codes includes a classification of horizontal obscuration into categories of fog, ice fog, steam fog, mist, haze, smoke, volcanic...
or light mist
Mist
Mist is a phenomenon of small droplets suspended in air. It can occur as part of natural weather or volcanic activity, and is common in cold air above warmer water, in exhaled air in the cold, and in a steam room of a sauna. It can also be created artificially with aerosol canisters if the...
, used to refer to the milky look of the sky when cirrostratus is present.
See also
- Stratus cloudStratus cloudA stratus cloud is a cloud belonging to a class characterized by horizontal layering with a uniform base, as opposed to convective clouds that are as tall or taller than wide . More specifically, the term stratus is used to describe flat, hazy, featureless clouds of low altitude varying in color...
- Altostratus cloudAltostratus cloudAltostratus is a cloud belonging to a class characterized by a generally uniform gray to bluish-gray sheet or layer, lighter in color than nimbostratus and darker than cirrostratus. The sun can be seen through thin altostratus, but thicker layers can be quite opaque...
- Nimbostratus cloudNimbostratus cloudA Nimbostratus cloud is characterized by a formless cloud layer that is almost uniformly dark gray. "Nimbo" is from the Latin word "nimbus", which denotes precipitation. It is generally a stratiform cloud of moderate vertical development that produces precipitation, developing cloud bases between...
- Cirrostratus nebulosusCirrostratus nebulosusCirrostratus nebulosus is a type of cirrostratus cloud. The name cirrostratus nebulosus is derived from Latin, meaning "full of vapor, foggy, cloudy, dark"...
- Cirrostratus fibratusCirrostratus fibratusCirrostratus fibratus is a type of cirrostratus cloud. The name cirrostratus fibratus is derived from Latin, meaning "fibrous". Cirrostratus fibratus is one of the two most common forms that cirrostratus often takes, with the other being cirrostratus nebulosus. They are formed from strong,...
- Altostratus undulatus cloudAltostratus undulatus cloudThe altostratus undulatus is a type of low altocumulus cloud with signature undulations within it. These undulations may be visible , but frequently they are indiscernible to the naked eye...
- Fractus cloudFractus cloudFractus clouds are small, ragged cloud fragments that are usually found under an ambient cloud base. They form or have broken off from a larger cloud, and are generally sheared by strong winds, giving them a jagged, shredded appearance. Fractus have irregular patterns, appearing much like torn...