by Staff Writers
Washington DC (SPX) Jul 08, 2011
Under certain conditions, private and commercial propeller planes and jet aircraft may induce odd-shaped holes or canals into clouds as they fly through them. These holes and canals have long fascinated the public and now new research shows they may affect precipitation in and around airports with frequent cloud cover in the wintertime.
Here is how: Planes may produce ice particles by freezing cloud droplets that cool as they flow around the tips of propellers, over wings or over jet aircraft, and thereby unintentionally seed clouds.
These seeding ice particles attract more moisture, becoming heavier, and then "snow out" or fall out of the cloud as snow along the path of a plane, thereby creating a hole in a cloud.
The effects of this inadvertent cloud seeding are similar to the effects of the intentional seeding of clouds: that is, both processes may increase the amount of precipitation falling from clouds.
The study, which was partially funded by the National Center for Atmospheric Research (NCAR) in Boulder, Colo., appears in the July 1, 2011 issue of the journal Science. NCAR is partially funded by the National Science Foundation.
"It is unlikely that the hole-punching ability of planes affects global climate," says Andrew Heymsfield of NCAR, the study's lead author.
But because the hole-punching ability of planes is particularly high when they fly through low subfreezing clouds, major airports that are covered in low clouds during winter are particularly vulnerable to precipitation associated with this inadvertent seeding.
This vulnerability means it may be necessary to de-ice planes more frequently, Heymsfield says. Also, because weather station records that climate modelers incorporate into climate predictions are housed at airports in the Arctic and Antarctic, climate predictions for these areas may be influenced by local weather conditions caused by inadvertent seeding near those airports.
Heymsfield says that his team's latest research built on a paper published by the team last year on a similar topic in the Bulletin of the American Meteorological Society by:
1) evaluating the exact types of aircraft that produce airplane induced holes and canals;
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Sounding rockets study how winds in space drive currents in the upper atmosphere
Greenbelt MD (SPX) Jul 06, 2011
Some 50 miles up in the sky begins a dynamic region of the atmosphere known as the ionosphere. The region is filled with charged particles created by extreme ultraviolet radiation from the sun. At the base of the ionosphere, charged particle motions create a global current called the "atmospheric dynamo." Generally moving in loops from the equator to the poles, the dynamo changes daily bas ... read more
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