“Night shining” clouds above Polar Regions may be partly due to global warming

December 11th, 2007 - 6:30 pm ICT by admin  

Washington, Dec 11 (ANI): Observations from a NASA satellite has led researchers to suggest that the phenomenon of clouds shining in the night 50 miles above the polar regions, may be partly due to global warming.
Known as noctilucent or “night-shining” clouds, they are visible by night because they are so high above the Earth that they are illuminated by sunlight, while the ground below is in darkness.
Though scientists have been keeping tabs on the clouds for about 27 years through a series of solar-watching satellites, NASA’s AIM (Aeronomy of Ice in the Mesosphere) satellite is part of the first mission devoted to studying the clouds exclusively.
AIM observed these clouds during the first season of its operations, when it confirmed a long-held suspicion that a summertime radar phenomenon observed at the polar regions was due to signals bouncing off ionized ice crystals in the upper atmosphere.
Researchers believe that these clouds are more numerous and denser than expected due to changes in Earth’s climate.
“These clouds are changing in ways that we don’t understand. They appear more frequently than in the past and form at lower altitudes, which, may be due to a buildup of carbon dioxide in the lower atmosphere,” said AIM principal investigator Jim Russell. “The gas traps heat and leaves the upper mesosphere colder than normal,” he added.
The scientists also believe that a difference of just 5 degrees Fahrenheit has profound effects on the clouds’ structure and motion. “A small change in temperature is causing a dramatic change in cloud behavior,” Scott Bailey, deputy principal investigator for AIM, told Discovery News.
Scientists are most surprised after seeing so much variation in these clouds.
“It’s the changes day-to-day that really surprised us,” said Bailey. “Even from orbit to orbit, we can see differences in the behavior of the clouds,” he added.
Analysis of the chemical composition of the clouds is under way. (ANI)

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