Mammatus clouds are some of the most unusual and distinctive cloud formations.
They appear with a series of bulges or pouches emerging from the base of a cloud, sometimes known as bubblewrap clouds.
The shape of mammatus formations can vary widely; from the classic protruding shape, to a more elongated tube hanging from the cloud above.
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What are Mammatus clouds?
Mammatus clouds are usually formed in association with large cumulonimbus clouds. Typically, turbulence within the cumulonimbus cloud will cause mammatus to form, especially on the underside of the projecting anvil as it rapidly descends to lower levels. This reverses the usual cloud-forming process of upward growth, making for an uneven cloud base.
Are mammatus clouds a weather forecasting aid?
Mammatus often form in association with Cumulonimbus clouds, bringing thunderstorms due to their huge mass of unstable air. Mammatus clouds generally form in the most unstable cumulonimbus, meaning that there is also a chance of hail, heavy rain and lightning in the vicinity, and if the air is cold enough during winter they can produce snow. Sometimes Mammatus may form on other cloud types which produce no rain, though this is far less common.
Mammatus comes from the Latin mamma which translates to “udder” or “breast”. Their striking appearance is most visible when the sun is low in the sky and the sunlight frames their pouches. This supplementary feature is a firm favourite with many meteorologists as well as cloud and photography enthusiasts.
Mammatus usually form on the base of a cumulonimbus anvil, but they have also been sighted to form on other cloud types, such as stratocumulus, altostratus and altocumulus. Mammatus have also been observed to form on the underside of volcanic ash clouds.
