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 is casts ; cast 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 pellet .

Grey is arranged or whitish field , roll or bundle , with rounded edge , at low level ; regularly arrange element . Size 5Â ° – 10Â ° ( 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.