After the events of September 11th, the Federal Aviation Administration shut down all U.S. commercial air traffic for 3 days. This enabled scientists to a unique opportunity and study the influence of high-flying aircraft on Earth's climate.
One way that aircraft may affect climate is through their cloud like contrails, which appear behind jets flying at high altitude.
In a series of photos taken Sept. 12, individual cloud trails of high-flying military aircraft stand out clearly in a nearly cloud-free region west of Washington, D.C. In just a few hours, six contrails—each of which started out a few meters wide—spread to cover more than 20,000 square kilometers.
David J. Travis, an atmospheric scientist at the University of Wisconsin-Whitewater and his colleagues looked at the average diurnal temperature range (DTR)—the difference between the day's high and low temperatures. Their findings contend that contrails can significantly affect climate.
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