Pat Shingleton: "Contrails - Leaving a Trail..."
For the last few days our blue skies have been streaked with contrails. They form when hot engine air mixes with super cold air in the troposphere. Most contrails disappear and others form cirrus clouds, gathering incoming sun-energy and escaping infrared heat from the earth. The International Journal of Climatology reports that contrails can affect cloudiness and possibly the climate. Researchers examined data from World War II Allied bombing raids on more than 1,000 sorties from 1943 to 1945. They compared data on raid-free days and found that out of 20 raids, May 11,1944 was the best case study - 1,444 aircraft left airfields across southeast England into a clear sky. The contrails from these aircraft suppressed the temperature by a degree.