Cumulonimbus

Cumulonimbus are a dense and vertically developed cloud that produces thunderstorms. The cloud can bring heavy showers, hail, lightning, high winds and sometimes tornadoes.

Cumulonimbus clouds are towering, anvil-shaped nimbus clouds responsible for heavy rain, snow, and hail.

Cumulonimbus clouds are associated with thunderstorms.

The one to the east (which at the moment seemed to be leaping straight out of the heart of a sinister slaty-purple patch of cumulonimbus) drained the Lake of the Hanging Glaciers; that to the west a desolate rock and ice-walled valley which was rimmed by some of the highest summits in the Selkirks.