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|Satellite Imagery Captures Contrails and Their Shadows|
Posted 13 days ago
Recent imagery from the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument shows condensation trails over Alaska’s eastern Interior and over the eastern Brooks Range.
A condensation trail, or “contrail,” is a thin cloud left behind when the ambient humidity and temperature of the air allows the water vapor in an aircraft’s exhaust to condense and form a cloud. Some contrails dissipate rather quickly, while others may linger and even spread out over time, again all depending on the conditions of the ambient atmosphere.
This particular case is from the afternoon of Friday, October 7, and shows the true colors the human eye would see if we had hitched a ride on the satellite. Note the corkscrew contrails over the eastern Interior, and the more linear contrails over the eastern Brooks Range. At this time of year in northern Alaska the sun hangs low over the southern horizon during the afternoon, and shadows from the contrails can be seen on the ground below, offset slightly to the north.
Eielson Air Force Base’s “Red Flag-Alaska” exercise kicked off on October 6th, so these contrails appearing the following day may be associated with those activities. Contrails from civilian aircraft tend to appear more linear than the wide looping tracks evident in this imagery.
More information about the VIIRS instrument is available at http://ncc.nesdis.noaa.gov/VIIRS/ More information about Red Flag-Alaska is available at http://www.eielson.af.mil/Info/REDFLAG-Alaska.aspx