mammatus

[ muh-mah-tuhs, muh-mat-uhs, mam-uh-tuhs ]

noun

, Meteorology.

, plural mam·ma·tus.

1. a formation of pouchlike clouds created within a cumulonimbus and hanging from its underside, typically as a short-lived phenomenon associated with severe weather: mamma ²( def 2 ).

   The spectacle of mammatus is the opposite of fluffy, floating clouds—it’s like “thundercloud udders” filled with downward-pulling cold moisture.

Word History and Origins

Origin of mammatus¹

Coined in 1894 by English meteorologist William Clement Ley (1840–1896); from Latin: “breastlike, having breasts,” adjective derivative of mamma mamma ²( def )

Example Sentences

According to the National Oceanic and Atmospheric Administration, mammatus clouds are formations with rounded, smooth, sack-like protrusions hanging from the underside of a cloud.

From Fox News

After the storms moved through, heavy "mammatus clouds" could be seen in the skies above.

From Fox News

"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," according to the forecast office.

From Fox News

There might be an ominous display of mammatus clouds, the iconic pouch-like bags that hang beneath foreboding storms that usually are a sign of turbulence in the atmosphere.

From Washington Post

The storm was particularly striking at this stage due to the eruption of mammatus cloud from the anvil that was constantly being lit up with lightning.

From BBC