In this fantastic capture by Michel Filion, we see rare mamatus clouds during a storm in Quebec, Canada. The photo was taken from the back of the photographer’s house.

Mammatus, also known as mammatocumulus (meaning “mammary cloud” or “breast cloud”), is a meteorological term applied to a cellular pattern of pouches hanging underneath the base of a cloud. The name mammatus is derived from the Latin mamma (meaning “udder” or “breast”). Mammatus are most often associated with the anvil cloud and also severe thunderstorms. [Source]

Typically composed primarily of ice, they can extend for hundreds of miles in each direction and individual formations can remain visibly static for ten to fifteen minutes at a time. While they may appear foreboding they are merely the messengers – appearing around, before or even after severe weather. [Source]