Noctilucent Clouds as seen from the ISS

This image was taken from the ISS as it passed over the Tibetan Plateau, on June 13, 2012, when  polar mesospheric clouds were also visible to aircraft flying over Canada.   Image credit: NASA, Expedition 31 crew, ISS

Polar mesospheric clouds are at the peak of their visibility, in both the Northern and Southern Hemisphere, during their respective late spring and early summer seasons.

In addition to the still image above, the ISS crew took this 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.

via earthobservatory