Cloud Types and Precipitation

There are ten main cloud types, which are further divided into 27 sub-types according to their height shape, colour and associated weather, Clouds are categorised as low (from the earth's surface to 2.5 km), middle (2.5 to 6 km), or high (above 6 km). They are given Latin names which describe their characteristics, e.g. cirrus (a hair), cumulus (a heap), stratus (a layer) and nimbus (rain-bearing). Clouds generally look white with some clouds appearing to be grey or dark grey according to their depth and shading from higher cloud.

Typical Examples of the 10 Main Cloud Types

High Level Clouds (above 6 km)


Cirrus: high level, white tufts or filaments; made up of ice crystals.
No precipitation.


Cirrocumulus: high level, small rippled elements; ice crystals.
No precipitation.


Cirrostratus: high level, transparent sheet or veil, halo phenomena; ice crystals.
No precipitation.

Middle Level Clouds (2.5 to 6 km)


Altocumulus: middle level layered cloud, rippled elements, generally white with some shading.
Precipitation: May produce light showers.


Altostratus: middle level grey sheet, thinner layer allows sun to appear as through ground glass.
Precipitation: rain or snow.


Nimbostratus: thicker, darker and lower based sheet.
Precipitation: heavier intensity rain or snow.

Low Level Clouds (below 2.5 km)


Stratocumulus: low level layered cloud, series of rounded rolls, generally white.
Precipitation: drizzle.


Stratus: low level layer or mass, grey, uniform base; if ragged, referred to as 'fractostratus'.
Precipitation: drizzle.


Cumulus: low level, individual cells, vertical rolls or towers, flat base.
Precipitation: showers or snow.


Cumulonimbus: low level, very large cauliflower-shaped towers to 16 km high, often 'anvil tops'. Phenomena: thunderstorms, lightning, squalls.
Precipitation: showers or snow.