Karela Fry

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Aircrafts change the weather

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Inside Science has an article on condensation trails (contrails) from high-flying jets, and how they affect the weather:

The idea that contrails affect weather is not entirely new. After the attacks on Washington, D.C. and New York on 9/11, American skies were clear of all aircraft for three days. Researchers reported a 2 degree Fahrenheit change in the variation between high and low temperatures — which disappeared when commercial flights resumed.

But that conclusion is controversial.

MacKenzie, Roger Timmis, and Annette Ryan at Lancaster, working with the Royal Air Force Museum at Hendon, went back through the records from 1943 to the war’s end in 1945. With the help of the museum staff, they were able to center on the May 11 raid. From pilot briefings, they found the planes in the morning mission produced contrails when they reached 12,000-15,000 feet, relatively low, so they concentrated on that mission. There were no missions the next few days and the weather did not change notably, providing something of a control.

The morning squadron was enormous, 363 B-24s and 536 fighters in escort. The target was marshalling yards in France, places where the Germans assembled troops. All or most of the planes produced contrails.

Using data from weather stations on the ground, they looked at the increase of temperature through the morning from stations covered by the contrail cloud and found the temperature increase during the morning lagged by about 2 degrees Fahrenheit from stations not under the cloud. The contrails, being white, were reflecting sunlight back into space.

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Written by Arhopala Bazaloides

August 15, 2011 at 7:38 pm

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