July 11, 2011

WWII Air Raids Had Effect On Weather

"¨World War II bombing raids conducted during the 1940s could provide valuable insight as to how modern aviation technology is affecting our weather today, according to the results of a study recently published in the International Journal of Climatology.

"¨According to a July 7 press release from journal publishers Wiley-Blackwell, Professors Rob MacKenzie, now at the University of Birmingham, and Roger Timmis of the Environment Agency, analyzed historical data in order to determine the levels of Aircraft Induced Cloudiness (AIC) caused by Allied bombers departing from England for mainland Europe between the years of 1943 and 1945.

"¨Those years were chosen because by that time, the US Army Air Force (USAAF) had joined the campaign, the researchers point out. According to Tim Wall of Discovery News, the addition of the American aircraft "led to a huge increase in the number of planes based in East Anglia, the Midlands and the West Country"¦ That made distinguishing airplane-influenced climate data more clearly discernible from unaffected nearby climatic conditions."

"¨"Witnesses to the huge bombing formations recall that the sky was turned white by aircraft contrails," MacKenzie said in a statement. "It was apparent to us that the Allied bombing of WWII represented an inadvertent environmental experiment on the ability of aircraft contrails to affect the energy coming into and out of the Earth at that location."

"¨As part of their research, MacKenzie and colleague looked specifically at May 11, 1944. On that date, 1,444 aircraft took off from various airfields from southeastern England. Before they launched, conditions were reportedly clear with just a few clouds.

"¨However, after the hot, aerosol-laden air expelled from the plane engine mixed with cooler air from atmosphere, it created contrails and "significantly suppressed the morning temperature increase across those areas which were heavily over flown," according to the Wiley-Blackwell press release.

"¨In fact, Wall notes that the areas which the aircraft flew over "stayed an average .8 degrees Celsius (1.44 degrees F) cooler than surrounding areas from about 7 a.m. to 1 p.m."

"¨"This is tantalising evidence that Second World War bombing raids can be used to help us understand processes affecting contemporary climate," MacKenzie told Discovery News. "By looking back at a time when aviation took place almost entirely in concentrated batches for military purposes, it is easier to separate the aircraft-induced factors from all the other things that affect climate."


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