Night-shining clouds high in the atmosphere over the southern polar region appear in shades of blue and orange in this astronaut photo from January 30, 2010.
In June 2007, the Space Shuttle crew visiting the International Space Station (ISS) observed spectacular polar mesospheric clouds over north-central Asia. TThe red-to-dark region at the bottom of the image is the dense part of the Earth’s atmosphere.
Polar mesospheric clouds (also known as noctilucent, or “night-shining” clouds) are transient, upper atmospheric phenomena that are usually observed in the summer months at high latitudes (greater than 50 degrees) of both the Northern and Southern Hemispheres. They appear bright and cloudlike while in deep twilight. They are illuminated by sunlight when the lower layers of the atmosphere are in the darkness of Earth’s shadow.
The rare night-shining clouds seen in this photo are both forming more frequently and becoming brighter, trends that point to changes in the atmosphere linked to greenhouse gases.
High-altitude night-shining clouds form and dissipate on a daily cycle revealed in this series of images made from data from the Ozone Monitoring Instrument on NASA’s Aura satellite.