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noctilucent cloud |
Also found in: Acronyms, Wikipedia, Hutchinson | 0.01 sec. |
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noctilucent cloud [¦näk·tə¦lü·sənt ′klau̇d] (meteorology) A cloud of unknown composition which occurs at great heights and high altitudes; photometric measurements have located such clouds between 45 and 54 miles (75 and 90 kilometers); they resemble thin cirrus, but usually with a bluish or silverish color, although sometimes orange to red, standing out against a dark night sky. How to thank TFD for its existence? Tell a friend about us, add a link to this page, add the site to iGoogle, or visit webmaster's page for free fun content. |
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| Cloud experts have sighted beautiful noctilucent clouds, or silvery blue ice clouds, over Colorado--1,000 kilometers farther south than usual. Noctilucent clouds develop in the mesosphere at an altitude of 85 kilometers. Noctilucent clouds have puzzled and awed cloud watchers since they were discovered a century ago. |
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