Ephemeral
clouds appear in this astronaut photo taken from the International Space
Station over western Mongolia in the pre-dawn hours of July 22, 2008.
Night-shining
(noctilucent) clouds go by the official name of polar mesospheric clouds,
showing up briefly in the upper atmosphere during summer months at the high
latitudes of both the northern and southern hemispheres. The clouds in this
image bear resemblance to cirrus clouds found as high as 60,000 feet (18 km),
but these actually occupy altitudes of 250,000 to 280,000 feet (76 to 85 km).
This
image was taken at an altitude of just over 200 miles (321 kilometers) above
the Earth. The space station crew has acquired many similar cloud images for
research relating to the International Polar Year, and scientists suspect that
increased observations of such clouds relate to changes in the global climate.
— NASA and SPACE.com Staff
Credit: NASA
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