Cloud identification guide

Huge cloud tower, sometimes with anvil. Thunderstorm possible.

Hooks, feathers, bands or patches with silky shimmer.

Isolated, puffy cloud with sharp outlines.

Transparent milky or fibrous veil, casts shadow, produces halo.

Thin, pure white fields of small grains or ripples at a high level. Size < 1°

Smooth, extensive layer; casts no shadow, even if Sun/Moon is recognizable as a blurred dot.

White/grey patches (turreted, lens shaped or balls of cotton), sheets or structured layer with undulations or rolls. Size 1° - 3°

Dark rain cloud or bright snow cloud. Usually continuous rain, snow or ice pellets.

Grey or whitish fields, rolls or bundle, with rounded edges, at low level; regularly arranged elements. Size 5° - 10° (full hand)

Grey-whitish low layer, sometimes with drizzle or snow grains. If Sun/Moon is visible its outline is clear. Can occur in fragments.