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Polar mesospheric cloud season underway

July 30, 2010
PMCs

Northern Hemisphere polar mesospheric clouds, mapped from the AIM satellite in this June 21 image, can be seen from the ground when they reflect light after sunset.

According to Cora Randall, CU professor and LASP research associate, the Aeronomy of Ice in the Mesosphere (AIM) Cloud Imaging and Particle Size (CIPS) instrument saw this season’s first polar mesospheric clouds on May 28. Polar mesospheric clouds, also called noctilucent or “night shining” clouds, form at about 50 miles above Earth’s surface and can be seen when they reflect light after sunset. The Northern Hemisphere cloud season generally begins in late May and lasts until late August; in the Southern Hemisphere, the season goes from late November to late February.

Although the 2010 season has begun, Randall noted the timing of this year’s first cloud detection.  She said, “The season appears to be starting more slowly than in past years.”

Scientists are not sure what has caused this change, but hope that ongoing data from AIM will further our understanding of mesospheric weather patterns.  Scientists believe the timing and duration of polar mesospheric cloud formation can provide understanding about climate change and the link between mesospheric and tropospheric weather patterns.

For more information on AIM/CIPS visit: http://www.nasa.gov/mission_pages/aim/index.html

View more images at http://lasp.colorado.edu/aim/browse-images.php