Bright white streaks suspended in the sky, Cirrus clouds are characterized by hair like filaments which may often resemble a fluctuating horses's tail and this is why they are often gently referred to as "mare tails". Cirrus clouds are very eye appealing clouds, their presence creates spectalur skies often whipped up by the wind and resembling an artist's canvas with diluted, transparent strokes.
Cirrus clouds are the highest clouds of all. They are located in the troposphere at over 8000 meters, that is 23,000 feet. They are not seen gliding through the sky as cumulus clouds, because of their distance, making movement quite imperceptible. In reality, they are quite fast moving clouds, faster than cumulus clouds because of the strong winds blowing up to 150 miles per hour in the troposphere.
Cirrus clouds form when vapor droplets freeze turning into ice crystals. Their hair like filaments are caused by the heaviest ice crystals precipitating. Basically, cirrus clouds can be referred to as precipitating clouds. The ice crystals though do not make it to the ground as they evaporate upon descent, once in contact with warmer air. They are sort of ''melting'' clouds.
While the most comon Cirrus clouds are of the delicate streak type, there are different varities that may appear in the sky;
Cirrus Fibratus: these are the hair like filament shaped cirrus clouds, also known as mare's tails. The filaments are actual streaks of ice crystals that are descending and melting as they meet warmer air.
Cirrus Uncinus: these are similar to cirrus fibratus but they are characterized by filaments ending in typical hook shapes.
Cirrus Spissatus: these are quite different from the regular cirrus types. They appear thick and with a grayish tint when viewed towards the sun.
Cirrus Castellanus: the name deriving from the Spanish word castle, these cirrus are characterized by ''turrets''.
Cirrus Floccus: these are cotton like clouds divided in tufts with streaks precipitating below.
Among the various types of Cirrus clouds some are even man-made. The streaks found on the sky after an airplane has passed are really nothing more than man made Cirrus clouds. The principle is the same, the exhaust of the aircraft's engines release vapor which at that height, quickly turn into ice crystals. As the ice crystals descend, they meet warmer air and melt, causing the trace to dissipate slowly.
Cirrus clouds are not rain or snow clouds, however they may be warning signs of upcoming changes. Their presence is often followed by more significant clouds that may make a distinct change in the weather. As other clouds, they are pretty reliable predictors of weather, with their presence often indicating a weather change in the next 24 hours.