cumulonimbus

American  

[kyoo-myuh-loh-nim-buhs] / ˌkju mjə loʊˈnɪm bəs /

noun

Meteorology.

• cumulonimbus
  plural

1. a cloud of a class indicative of thunderstorm conditions, characterized by large, dense towers that often reach altitudes of 30,000 feet (9,000 meters) or more, cumuliform except for their tops, which appear fibrous because of the presence of ice crystals: occurs as a single cloud or as a group with merged bases and separate tops.

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cumulonimbus British  

/ ˌkjuːmjʊləʊˈnɪmbəs /

noun

1. meteorol a cumulus cloud of great vertical extent, the top often forming an anvil shape and the bottom being dark coloured, indicating rain or hail: associated with thunderstorms

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cumulonimbus Scientific  

/ kyo̅o̅m′yə-lō-nĭm′bəs /

• cumulonimbi
  plural

1. An extremely dense, vertically developed cloud with a low, dark base and fluffy masses that tower to great heights. Cumulonimbus clouds usually produce heavy rains, thunderstorms, or hailstorms.

2. Also called thundercloud

3. See illustration at cloud

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Other Word Forms

Noun Inflected Forms

• cumulonimbus
  plural

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Etymology

Origin of cumulonimbus

First recorded in 1885–90; cumulo- + nimbus

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Example Sentences

See Examples For:

cumulonimbus

Near the hurricane's eyewall, the release of latent heat fuels powerful convection, causing warm, moist air to surge upward and form towering cumulonimbus clouds.

From Science Daily ● Oct. 16, 2026

Also called a cumulonimbus flammagenitus, they can occur during volcanic eruptions or, as in this case, when a wildfire roasts the air near the ground, causing it to rise quickly.

From Barron's ● Jul. 27, 2026

If the fire is powerful enough and the atmosphere is unstable, that cloud can grow into a towering cumulonimbus - the same type of cloud associated with thunderstorms.

From BBC ● Jul. 27, 2026

"The heat near the ground has been forced up into the freezing layers of the troposphere, cooling rapidly and creating giant cumulonimbus clouds and thundery downpours."

From BBC ● Jun. 26, 2026

A large tract of cumulonimbus cloud had rolled in.

From "The London Eye Mystery" by Siobhan Dowd

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