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Concept information

Preferred term

polar mesospheric cloud  

Definition(s)

  • Noctilucent clouds, or night shining clouds, are tenuous cloud-like phenomena in the upper atmosphere of Earth. When viewed from space, they are called polar mesospheric clouds (PMCs), detectable as a diffuse scattering layer of water ice crystals near the summer polar mesopause. They consist of ice crystals and from the ground are only visible during astronomical twilight. Noctilucent roughly means "night shining" in Latin. They are most often observed during the summer months from latitudes between ±50° and ±70°. Too faint to be seen in daylight, they are visible only when the observer and the lower layers of the atmosphere are in Earth's shadow, but while these very high clouds are still in sunlight. Recent studies suggest that increased atmospheric methane emissions produce additional water vapor once the methane molecules reach the mesosphere – creating, or reinforcing existing noctilucent clouds. (Wikipedia, The Free Encyclopedia, https://en.wikipedia.org/wiki/Noctilucent_cloud)

Broader concept(s)

Synonym(s)

  • night shining cloud
  • noctilucent cloud

In other languages

URI

http://data.loterre.fr/ark:/67375/MDL-G5HH91S7-G

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