These mystifying clouds are called Polar Mesospheric Clouds, or PMCs, when they are viewed from space and referred to as "night-shining" clouds or Noctilucent Clouds, when viewed by observers on Earth. The clouds form in an upper layer of the Earth’s atmosphere called the mesosphere during the summer and can be seen from the high latitudes on Earth.
Image Courtesy of NASA/Veres Viktor

Noctilucent Clouds

There is a special kind of cloud that is found in the mesosphere, which is the third layer of the Earth's atmosphere. These clouds are called noctilucent clouds (NLC’s) or polar mesospheric clouds (PMC’s). Noctilucent means night-shining. The clouds are called that because they are seen best right after sunset and they glow blue-white.

Like lower clouds we see more often, NLC's are made of frozen water. They are important to study because they may be a sign of climate change on Earth, like global warming. Scientists will look into this possibility with a new atmospheric mission, called AIM (The Aeronomy of Ice in the Mesosphere).

Last modified February 10, 2009 by Becca Hatheway.

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