In this article we find out more about the distinctive mammatus clouds. What gives them their distinctive shape and when do they form?
Mammatus clouds are some of the most unusual and distinctive clouds formations with a series of bulges or pouches emerging through the base of the cloud.
Mammatus clouds are usually formed in association with large cumulonimbus clouds, particular when these are forming large thunderstorms. Typically turbulence within the cumulonimbus cloud will cause the mammatus to form, especially on the underside of the projecting anvil.
Their striking appearance is most visible when the sun is low in the sky and their pouches are framed by the sunlight.
Last updated: 5 August 2014