Types of Clouds

High Clouds

Description

Cirrus

Detached clouds in the form of white delicate filaments or white or mostly white patches or narrow bands; have fibrous (hairlike) appearances or a silky sheen or both.

Cirrocumulus

Thin white patch, sheet, or layer of cloud without shading; composed of very small elements in the form of grains, ripples, etc., merged or separate, and more or less regularly arranged.

Cirrostratus

Transparent, whitish cloud veil of fibrous or smooth appearance, totally or partly covering the sky, and generally producing halo phenomena.

Middle Clouds

Altocumulus

White or grey (or both white and grey) patch, sheet, or layer of cloud, generally with shading; composed of rounded masses, rolls, etc., which are sometimes partly fibrous or diffuse and which may or may not be merged; regularly arranged small elements.

Altostratus

Greyish or bluish cloud sheet or layer of striated, fibrous, or uniform appearance; totally or partly covers the sky; parts thin enough to reveal the sun at least vaguely; does not show halo phenomena.

Nimbostratus

Gray cloud layer, often dark; appearance is rendered diffuse by more or less continuously falling rain or snow, which in most cases reaches the ground; thick enough throughout to blot out the sun; low, ragged clouds frequently occur below the layer, with which they may or may not merge.

Low Clouds

Stratocumulus

Gray or whitish (or both grey and whitish) patch, sheet, or layer of cloud which almost always has dark parts; composed of rounded masses, rolls, etc., which are mostly nonfibrous and which may or may not be merged; regularly arranged small elements.

Stratus

Generally grey cloud layer with fairly uniform base; may give drizzle, ice prisms, or snow grains; when sun is visible through the cloud, its outline is clearly discernible; stratus does not produce halo phenomena except possibly at very low temperatures; sometimes stratus appears in the form of ragged patches.

Cumulus

Detached clouds, generally dense and with sharp outlines, developing vertically in the form of rising mounds, domes, or towers, of which the bulging upper part often resembles a cauliflower; sunlit parts of these clouds are mostly brilliant white; their base is relatively dark and horizontal; sometimes cumulus is ragged.

Cumulonimbus

Heavy and dense cloud, with a considerable vertical extent, in the form of a mountain or huge towers; at least part of its upper portion is usually smooth, or fibrous or striated, and nearly always flattened; this part often spreads out in the shape of an anvil or vast plume; under the base of this cloud, which is often very dark, there are frequently low, ragged clouds either merged with it or not, and precipitation.