cumulonimbus

American  

[kyoo-myuh-loh-nim-buhs] / ˌkyu myə loʊˈnɪm bəs /

noun

Meteorology.

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

Inflected Forms

noun

• cumulonimbus
  plural

Etymology

Origin of cumulonimbus

First recorded in 1885–90; cumulo- + nimbus

Example Sentences

Heat released within the storm fuels towering cumulonimbus clouds known as "hot towers."

From Science Daily • Jun. 3, 2026

Thunderstorms are powerful and complex phenomena, with air inside a cumulonimbus storm cloud moving rapidly upwards and downwards.

From BBC • Aug. 24, 2024

Warm temperatures allow the atmosphere to hold more humidity, and that humidity is a prerequisite for building clouds—specifically, the tall, menacing cumulonimbus clouds that produce thunder and lightning.

From National Geographic • Sep. 12, 2023

Tornadoes — or rotating funnels of air connected to the Earth and either a cumulonimbus or the base of a cumulus cloud — are dangerous because of their immense power, which Houser barely escaped.

From Salon • Mar. 29, 2023

But unlike Adams, I was unaccustomed to peering down at cumulonimbus cells from 29,000 feet, and I therefore remained ignorant of the storm that was even then bearing down.

From "Into Thin Air" by Jon Krakauer