These dark clouds are associated with atmospheric ... Thunderhead clouds, or cumulonimbus clouds, are the towering giants of the cloud world, stretching up to the stratosphere.

However, if the air is particularly warm and humid, and the atmosphere above is much colder, cumulus clouds can rapidly grow vertically into cumulonimbus. When the edges of these clouds look ...

However, if the air is particularly warm and humid, and the atmosphere above is much colder, cumulus clouds can rapidly grow vertically into cumulonimbus. When the edges of these clouds look ...

The Met Office explains the phenomenon in more detail on its website: "Mammatus clouds are usually formed in association with large cumulonimbus clouds. Typically, turbulence within the ...