Low-level clouds

Help with identifying low-level clouds - cumulus, cumulonimbus, stratocumulus and stratus. The bases of these clouds are usually found at below 6,500 ft in the UK.

Stratus clouds

Height of base: 0 - 6,500 ft

Latin: stratus - flattened or spread out

Stratus clouds are very low-level grey layers or patches of clouds with fuzzy edges. They are the lowest clouds and sometimes appear at ground level in the form of mist or fog. Stratus clouds are a fairly uniform grey or white colour and may be accompanied by drizzle, snow or snow grains. If there are no other clouds above the layer of stratus cloud, the sun or moon may shine through.

Stratus cloud Stratus cloud

Cumulonimbus clouds

Height of base: 1,100 - 6,500 ft

Latin: cumulus - heap; nimbus - rainy cloud

Cumulonimbus are heavy and dense low-level clouds, extending high into the sky in towers, plumes or mountain shaped peaks. Commonly known as thunderclouds, the base is often flat and very dark, and may only be a few hundred feet above the Earth's surface. Cumulonimbus clouds are associated with extreme weather such as heavy torrential downpours, hail storms, lightning and tornados.

If there is thunder, lightning or hail, it's a cumulonimbus cloud rather than nimbostratus.

Cumulonimbus cloud (Photo: Matthew Clark) Cumulonimbus cloud (Photo: Matthew Clark)

Cumulus clouds

Height of base: 1,200 - 6,500 ft

Latin: cumulus - heap

Cumulus clouds are detached cauliflower shaped clouds usually spotted in fair weather. If they get bigger they can sometimes produce showers. The top of these clouds are mostly brilliant white when lit by the sun, although their base is usually relatively dark.

Cumulus cloud Cumulus cloud

Stratocumulus clouds

Height of base: 1,200 - 6,500 ft

Latin: stratus - flattened; cumulus - heap

Low-level clumps or patches of cloud varying in colour from bright white to dark grey. They normally have well defined bases and some parts much darker than others. They can be joined together or have gaps between them. Stratocumulus clouds can be present in all types of weather conditions, from dry settled weather to light rain and snow.

Stratocumulus clouds Stratocumulus clouds

For more information on cloud spotting and pictures of different types of clouds, view our Cloud types for observers Cloud types for observers (PDF, 4 MB) guide.

Last updated: 6 August 2014