noctilucent cloud


noc·​ti·​lu·​cent cloud ˌnäk-tə-ˈlü-sᵊnt- How to pronounce noctilucent cloud (audio)
: a luminous thin usually colored cloud seen especially at twilight at a height of about 50 miles (80 kilometers)

Examples of noctilucent cloud in a Sentence

Recent Examples on the Web An animation based on data from NASA’s AIM spacecraft shows the sky over Antarctica glowing blue at the start of noctilucent cloud season in the Southern Hemisphere. Tom Yulsman, Discover Magazine, 6 Dec. 2016 These conditions are ideal for spotting noctilucent clouds, shimmering blue clouds composed of ice crystals that form in the mesosphere some 50 miles above Earth. Justin Grieser, Washington Post, 21 June 2023 Did an earlier-than-normal shift to summer conditions in the lower atmosphere over Antarctica contribute to the early start of noctilucent cloud season there? Tom Yulsman, Discover Magazine, 6 Dec. 2016 Initially launched on April 25, 2007, the NASA probe orbited about 370 miles above Earth's surface and studied polar mesospheric clouds, which are also known as night-shining or noctilucent clouds. Ariana Garcia, Chron, 21 Mar. 2023 So scientists do not have a long satellite record showing the onset and evolution of the noctilucent cloud season over Antarctica. Tom Yulsman, Discover Magazine, 6 Dec. 2016 The team is the first to demonstrate noctilucent cloud formation is linked to water vapor cooling. Elizabeth Gamillo, Smithsonian Magazine, 10 Mar. 2021 Agencies could educate employees on how to recognize high-altitude balloons hit by moonlight, fireballs that look like floating orbs, noctilucent clouds that resemble extraterrestrial neural networks. Sarah Scoles, Wired, 3 Mar. 2020 But as days get shorter with the onset of fall, noctilucent clouds will fade from view. Andrew Fazekas, National Geographic, 1 Aug. 2019

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'noctilucent cloud.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


noctilucent "luminous in the dark," from Latin noct-, nox night entry 1 + -i- -i- + lucent

First Known Use

circa 1934, in the meaning defined above

Time Traveler
The first known use of noctilucent cloud was circa 1934

Dictionary Entries Near noctilucent cloud

Cite this Entry

“Noctilucent cloud.” Dictionary, Merriam-Webster, Accessed 22 Jul. 2024.

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