Ripples in the sky: Space Station astronaut captures mysterious 'night shining' clouds over Tibetan plateau

By Rob Waugh
PUBLISHED: 12:37, 28 June 2012 | UPDATED: 16:31, 28 June 2012
Space Station astronauts captured images of rare 'night shining' clouds as the craft passed over the Tibetan Plateau - high-altitude clouds which appear as delicate, shining threads against the darkness of space.
The clouds can only be seen from aircraft in flight, from the Space Station, or rarely from the ground at twilight - and shine at night because the ice crystals are lit up by the sun from beneath the visible horizon.

The clouds can only be seen from aircraft in flight, from the Space Station, or rarely from the ground at twilight - and shine at night because the ice crystals are lit up by the sun from beneath the visible horizon

The clouds - called 'polar mesospheric' clouds or 'noctilucent', night-shining clouds were photographed on June 13 by the crew of the ISS using a Nikon D2X.
In both the Northern and Southern Hemisphere, during their respective late spring and early summer seasons, polar mesospheric clouds are at the peak of their visibility.

On June 13, 2012, when this image was taken from the ISS as it passed over the Tibetan Plateau, polar mesospheric clouds were also visible to aircraft flying over Canada.
In addition to the still image above, the ISS crew took a time-lapse image sequence of polar mesospheric clouds several days earlier (June 5) while passing over western Asia. It is first such sequence of images of the phenomena taken from orbit.

Night-shining clouds seen from County Kerry, Ireland: In both the Northern and Southern Hemisphere, during their respective late spring and early summer seasons, polar mesospheric clouds are at the peak of their visibility

The clouds can only be seen from aircraft in flight, from the Space Station, or rarely from the ground at twilight - and shine at night because the ice crystals are lit up by the sun from beneath the visible horizon

Polar mesospheric clouds form between 47 to 53 miles above Earth’s surface when there is sufficient water vapour at these high altitudes to freeze into ice crystals.
The clouds are illuminated by the Sun when it is just below the visible horizon, lending them their night-shining properties. In addition to the polar mesospheric clouds trending across the center of the image, lower layers of the atmosphere are also illuminated. The lowest layer of the atmosphere visible in this image—the stratosphere—is indicated by dim orange and red tones near the horizon.

While the exact cause for the formation of polar mesospheric clouds is still debated—dust from meteors, global warming, and rocket exhaust have all been suggested as contributors—recent research suggests that changes in atmospheric gas composition or temperature has caused the clouds to become brighter over time.

Read more: http://www.dailymail.co.uk/sciencetech/article-2165940/Ripples-sky-Space-Station-astronaut-captures-mysterious-night-shining-clouds-Tibetan-plateau.html#ixzz1z7XphkH5