Mammatus cloud are known for their interesting appearance, as the clouds seem to have smooth round puffs (sort of like cotton balls), hanging from its underside. The name mammatus is derived from the Latin mamma (meaning “udder” or “breast”). [source]

Mammatus are mots often associated with severe thunderstorms and anvil clouds and often extend from the base of a cumulonimbus cloud; but are known to be found under other cloud types as well.

Below you will find a gallery of these fascinating clouds that were found on Wikimedia Commons and Flickr (click the photographer’s name beneath each photo to see the original post). To learn more about Mammatus clouds visit Wikipedia.