Cirrus clouds are detached, hair-like clouds found at high altitudes. They are made of ice crystals. The name of this type of clouds is derived from the Latin term cirrus, which means a “lock of hair”. All high clouds are a variety of cirrus, a common cloud type that can be seen at any time of the year.
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Characteristics of Cirrus Clouds
- Shape: layered, tufty or patchy
- Latin: cirrus – lock or tuft of hair
- Precipitation: light
- Species: Cirrus castellanus, fibratus, spissatus, and uncinus
- Variety: Intortus, vertebratus, radiatus, and duplicatus
- Altitude: between 5,000 and 13,700 m (16,500 and 45,000 ft)
- Classification: How-level clouds
These are white clouds, transparent and without internal shadows. They have a very long and fine threadlike structure. These clouds usually have a regular distribution in the form of parallel lines, either straight or sinuous. Occasionally they mix up and appear as interlaced or entangled clouds. The overall appearance is as if the sky has been covered by brush strokes.
Ci clouds indicate a sudden weather change within 24 hours. These clouds indicate a sharp decrease in temperature due to water vapor in the upper levels of the troposphere. Water vapor plays a major role in regulating air temperature because it absorbs solar energy and thermal radiation from the planet’s surface.
Because these clouds form in very high altitudes, they contain ice crystals. They are formed when humid air rushes a storm upward and it reaches the limit of the troposphere. When the storm completes its life cycle, the winds scatter anvil clouds across the sky and Ci clouds appear. They can be seen all over the world. They may indicate that a weather front is approaching.
Shape and color
Cirrus clouds have a silky and fibrous appearance and can be observed in the form of separate elements. They appear as if made up of delicate white threads, with a feathery appearance. They can also appear as tightly packed clouds, or as narrow bands. When they form, they are able to cast shadow on objects. Ci clouds are usually white and predict good weather.
Formation of Cirrus Clouds
These clouds are made of tiny ice crystals, as they form at very high altitudes. At these altitudes the temperature ranges from -40 ºC to -60 ºC. This layer of air mass has a high water vapor content. When the air is cooled enough to reach saturation, ice crystals are produced instead of water droplets.
The presence of many cirrus clouds in the sky can be a sign of a weather front. It also can indicate that there is a turbulence in the upper layers of the atmosphere. Cirrus clouds can also be the remnants of a storm. Large layers of Ci clouds typically indicate formation of hurricane and typhoon currents. However, if they appear as scattered clouds they are a sign of good weather.
Cirrus clouds and the Weather
Ci clouds contribute to both the greenhouse effect and the amount of sunlight reflected by the Earth. For this reason it is not clear whether the net effect of cirrus clouds is warming or cooling the Earth. The main scientific obstacle to better understand this phenomenon lies in the modeling of the albedo effect. Clouds that contain different shapes of crystals and vary in size, reflect different amounts of sunlight. Old models tended to underestimate the albedo effect of Ci clouds. Improving those models will improve climate predictions.
- Cirrus Castellanus: this species of cloud is uncommon, but can be expected to be seen on days when the atmosphere is unstable.
- Cirrus Fibratus: It is a fairly common occurrence in Ci clouds. They can produce a halo phenomena, as they’re composed of ice crystals.
- Cirrus Spissatus: is a thick cirrus cloud. This species of Ci cloud is fairly recognizable and distinct.
- Intortus: are high altitude cloud formations best described as an entangled or jumbled cirrus cloud.
- Radiatus: are cirrus clouds which are arranged in parallel rows. They appear to converge at a single point on the horizon when observed from the right angle.
- Vertebratus: Ci vertebratus clouds are formed in high altitude and their shape resembles a fish skeleton.
- Duplicatus: as the name suggests, these are Ci clouds of different types that can be observed at different altitudes.