Cirrostratus
Cirrostratus ( Latin: cirrus "lock of hair, a tuft of horse hair, plume" and stratus "extended, spread out, covered with a layer"; abbreviation : Cs ), also known as veils in German-speaking countries , are fine, translucent, structureless to fibrous veils made of ice crystals that form when large masses of warm air slowly rise, cool down and the moisture condenses . Although you often don't notice the clouds, they can reduce the sun's rays and thus the temperature - if they are denser, this is also quickly noticeable when the sun no longer shines at full power. They are also often harbingers of a warm front and thus a deterioration in the weather, which can be foreseen especially when they condense and slowly become "deeper" (to Altostratus ). In summer they can also be seen elsewhere in the sky. In contrast to the Altostratus ( As ), the Cirrostratus often creates halos . The observation of the train speed also helps to distinguish it from the thinner altostratus.
Special types of Cirrostratus are fibratus and nebulosus , as well as the subspecies duplicatus and undulatus . For special forms, accompanying and mother clouds, see the article cloud .
Physical structure and appearance
- Cirrostratus consists mainly of ice crystals.
- Cirrostratus can appear in the form of a fibrous veil in which thin stripes can be present ( fibratus ) or look like a fog-like veil ( nebulosus ). The edge of a cirrostratus veil is sometimes sharply demarcated, but more often frays cirrus-like.
- Cirrostratus is never so thick that objects on the earth do not cast shadows, except when the sun is low.
- The remarks about the color of cirrus clouds largely apply to cirrostratus as well.
- Halo phenomena are often observed in the thin cirrostratus; sometimes the cirrostratus veil is so thin that a halo is the only indication of its presence.
See also: contrails
Emergence
Cirrostratus forms when extensive layers of air are slowly lifted to sufficiently high heights. Cirrostratus can also arise from the growing together of cirrus or cirrocumulus parts or from ice crystals falling out of cirrocumulus. Cirrostratus can also form as the altostratus becomes thinner or a cumulonimbus cloud spreads as the anvil spreads.
difference to
Cirrus
Cirrostratus differs from Cirrus in that it appears in the form of a veil of mostly large horizontal extension.
Cirrocumulus and Altocumulus
Cirrostratus has a generally diffuse appearance and does not show any granular or rippled structure, scale-like parts, balls, rollers, etc., i.e. features that are characteristic of Cirrocumulus and Altocumulus .
Altostratus
Cirrostratus differs from Altostratus in that it is of lesser thickness and halo phenomena can occur. Cirrostratus near the horizon can be confused with Altostratus. The slowness of the perceptible movement as well as the changes in thickness and appearance is characteristic of Cirrostratus and gives a good clue for the differentiation of this cloud from Altostratus and Stratus .
stratus
Cirrostratus can be confused with very thin stratus , which can appear bright white at an angular distance of less than 45 degrees from the sun. However, Cirrostratus differs from Stratus in that it looks whitish everywhere and possibly has a fibrous structure. In addition, halos are often seen in Cirrostratus, while this is not the case with Stratus - except at very low temperatures .
Dry haze
Cirrostratus differs from a haze in that the latter is opalescent or has a dirty yellowish to brownish color. It is sometimes difficult to see cirrostratus through haze.
