We are going to talk about one of the high clouds par excellence, the cirrus or cirrus. They are separate clouds in the form of delicate white filaments, or narrow, white or almost white bands or banks. These clouds have a fibrous appearance, similar to human hair, or a silky sheen, or both at the same time. If you want to know more about the types of clouds, continue reading.
Cirrus clouds are made up of tiny ice crystals, as they form at high altitudes, generally between 8 and 12 km above sea level. At these altitudes, the temperature ranges between -40º and -60ºC. When an air mass with a high water vapor content cools to saturation, ice crystals are produced instead of water droplets. This phenomenon is known as reverse sublimation, in which water vapor is transformed directly into ice. The strong winds that predominate in the upper levels of the atmosphere contribute to the formation of characteristic tatters of cirrus clouds, giving them their distinctive appearance.
It is important not to confuse cirrus clouds with cirrostratus, since the latter always produce halo phenomena, an optical phenomenon where light creates rings around the sun or moon due to interaction with ice crystals. To better understand these clouds, we recommend reading about How cirrus clouds form and are predicted.
As for the weather conditions to which they are associated, it can be stated that when cirrus clouds appear in isolation, they are an indication of good time. However, if they advance in an organized manner and progressively increase towards the horizon (as in the previous image), this may signal a time change, indicating the approach of a front or low pressure system. On the other hand, when cirrus clouds appear across the wind, they could be related to a high-altitude jet stream. If you are interested in the topic of climate change and clouds, you will also find useful information.
For those interested in cloud photography, there are a few tips to follow. Cirrus clouds offer their best light when photographed at a 90º angle to the sun. Using a polarizing filter can help highlight the white of cirrus clouds and darken the blue of the sky, providing an attractive visual contrast. Another recommendation is to include terrestrial references in the shot to give context to the image. During sunset, the rays of the sun below the horizon make, through the phenomenon of refraction, cirrus clouds can take on hues ranging from yellow to orange, then to red, and finally to gray. This process is, curiously, the reverse of that of sunrise. If you want to know more about the importance of clouds in the climate, we invite you to investigate.
In the world of cirrus clouds, one can distinguish four species Main: fibratus, Uncinus, Spissatus y Floccus. Furthermore, each of these species can be divided into four varieties: Intortus, Radiatus, Vertebratus y Duplicatus.
Characteristics of cirrus cloud species
- Cirrus fibratus: It has a striated appearance and is the most common cirrus species.
- Cirrus uncinus: It is characterized by its hook shape, also known as a mare's tail.
- Cirrus spissatus: It is an especially dense form that typically forms from thunderstorm clouds.
- Cirrus floccus: It is shaped like tufts and often occurs in separate groups.
Varieties of cirrus clouds
- Intortus: This variety is characterized by its extremely contorted shape, often produced by Kelvin-Helmholtz instability, which occurs when layers of wind blow at different speeds.
- Radiatus: It has large radial bands that extend across the sky.
- Vertebratus: It occurs when the cirri are arranged side by side, similar to ribs.
- Duplicatus: Characterized by cirrus clouds that are arranged one on top of the other in layers.
Cirrus clouds often produce hair-like filaments called falling strands, which are formed by heavier ice crystals that fall from the cloud. These filaments are similar to the virgas that occur in liquid water clouds. The size and shape of these strands are influenced by differences in air movement, known as wind shear. For those interested in learning more about the formation of storm clouds, this might be helpful.
Cirrus cloud coverage varies throughout the day, with a decrease in presence common during the day and an increase at night. Satellite data, such as CALIPSO, indicate that cirrus clouds cover between 31% and 32% of the Earth's surface. This coverage can vary significantly depending on location; in some areas of the tropics, it can reach up to 70%, while in polar regions, this number can be as low as 10%. If you are interested in learning more about how it is form clouds, here you will find relevant information.
Formation and atmospheric characteristics of cirrus clouds
Cirrus clouds typically form when warm, dry air rises, causing water vapor to deposit on dust or metal particles at high altitudes. In general, the average altitude of cirrus clouds increases with decreasing latitude, although the altitude is always topped by the tropopauseThis phenomenon usually occurs at the front of a warm front.
The formation of cirrus clouds is influenced by the presence of organic aerosols that act as crystallization nuclei. However, research suggests that these cirrus clouds form more often on rocky or metallic particles than on organic ones. This relates to what was discussed in the article on clouds and weather phenomena that may influence training conditions.
Cirrus clouds are the highest clouds in the atmosphere, typically occurring at altitudes between 5,000 and 18,000 meters above sea level. In polar latitudes, they generally form at lower altitudes, while in tropical regions they can reach up to 18,000 meters. This demonstrates that the height at which cirrus clouds form can vary considerably depending on geographic location and atmospheric conditions.
Cirrus clouds can also be present at the tops of cumulonimbus clouds that develop during thunderstorms. As these clouds expand vertically, they can create an anvil that extends and forms cirrus clouds around them, contributing to their characteristic appearance. If you'd like to delve deeper into the topic of specific clouds, you can find interesting information.
Impact of cirrus clouds on climate and the environment
Cirrus clouds are not only visually attractive, but they also play an important role in global climate. They help both trap heat emitted by the Earth into space and reflect sunlight. This makes it unclear whether the net effect of cirrus clouds on Earth's temperature is significant. heating o cooling. It can be noted that these aspects are related to the study of the clouds in climate change, a topic that deserves to be analyzed in more depth.
Exploring the impact of cirrus clouds on climate is essential. Old climate models tended to underestimate the albedo (light-reflecting capacity) of these cirrus clouds, which can hamper our weather predictions. However, improvements in these models are leading to more accurate forecasts.
The presence of cirrus clouds is often indicative of frontal systems or disturbances linked to upper layers of the atmosphere. Additionally, cirrus clouds can be the remnants of a passing storm, and large layers of cirrus often accompany high-altitude flows of hurricanes and typhoons. For those seeking a more comprehensive analysis of the cloud ceilings, can be a valuable resource.
The study of cirrus clouds provides us with valuable insights into the atmosphere and its behavior. These clouds, although often subtle and ethereal, are key to understanding how Earth's atmosphere interacts with solar radiation and how this relates to our climate variability.
and if it is formed by ice structures ... why doesn't it fall? the ice weighs
in cali, on january 11, 2016, there was a cirrus cloud