Altocumulus clouds ( lat. Altocumulus , Ac ) - white , grayish or bluish clouds in the form of ridges, consisting of plates or flakes that can merge into a continuous cover. Formed at an altitude of 2 to 6 kilometers. They consist mainly of supercooled water droplets with a radius of 5-7 microns with fluctuations from 3 to 24 microns. The sun and moon shine through the thin edges of the high cumulus clouds; crowns are often observed around them. There are no gaps through the seals or they are very weak. Precipitation in the form of individual raindrops or snowflakes may fall from high cumulus clouds.
Content
Classification
Views
The type of cloud determines its shape and structure. Each cumulus cloud belongs to one of these species.
- Altocumulus stratiformis (Ac str.) - layered.
- Altocumulus lenticularis (Ac lent.) - Lenticular separate dense clouds with smooth outlines, which sometimes merge into vast masses.
- Altocumulus castellatus (Ac cast.) - tower-shaped. They are a white or grayish layer of clouds over which cumulus-like masses protrude like small domes or turrets .
- Altocumulus floccus (Ac floc.) - flaky, white, torn at the edges of the cloud with a relatively rapidly changing shape.
- Altocumulus volutus (Ac vol.) - "rolling".
Varieties
A kind of cloud determines the relative position and transparency of its parts. A cloud may exhibit features of several varieties, and varieties may be common to different cloud genera.
- Altocumulus translucidus (Ac trans.) - translucent. Usually from sharply demarcated elements and differ in heterogeneous density. In thin parts, luminaries or the sky can shine through the clouds.
- Altocumulus perlucidus (Ac pe.) - with gaps.
- Altocumulus opacus (Ac op.) - non-translucent dense clouds forming an almost continuous layer, on the lower surface of which waves, ridges or plates are distinguishable.
- Altocumulus undulatus (Ac und.) - wavy.
- Altocumulus radiatus (Ac ra.) - lucid.
- Altocumulus lacunosus (Ac la.) - full of holes.
Additional Features
Often, high cumulus clouds exhibit virga features β clouds with precipitation bands. There are other additional features, such as Asperitas .
Education
High cumulus clouds form due to many processes (this explains the large number of their varieties):
- wave motion of air at the boundaries of inversion (for example, in front of cold fronts and fronts of occlusion );
- wave movements on slightly inclined frontal surfaces;
- wave movements over the mountains (in these cases, a variety of Ac lent. is formed);
- convection of air in a layer above two kilometers (most often, Ac floc. and Ac cast. are formed this way);
- the spreading of thick cumulus clouds in a layer of 2-5 km, especially during inversion.
Photos
Links
- Wikimedia Commons has media files related to High Cumulus Clouds
- International Cloud Atlas / Altocumulus
- Photos of Altocumulus on CloudAppreciationSociety
- High Cumulus Clouds // Atlas of Clouds / Ed. A.H. Khrgiana . - L .: Gidrometeoizdat, 1957 .-- 68 p.