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David Travis of the University of Wisconsin-Whitewater and two colleagues measured the difference, over those three contrail-free days, between the highest daytime temperature and the lowest nighttime temperature across the continental U.S. They compared those data with the average range in day-night temperatures for the period 1971-2000, again across the contiguous 48 states. Travis's team discovered that from roughly midday September 11 to midday September 14, the days had become warmer and the nights cooler, with the overall range greater by about two degrees Fahrenheit.
Using results from a general circulation model simulation of contrails, the cirrus trends over the United States are estimated to cause a tropospheric warming of 0.28–0.38C decade, a range that includes the observed tropospheric temperature trend of 0.278C decade between 1975 and 1994.
Originally posted by Essan
Research into this continues, but the current consensus is that persistent contrails produce an overall net increase in temperature due to the reflection back of outgoing radiation at night and in winter. This effect is most noticeabe at higher latitudes and it may be one reason why Arctic regions are warming greater than other parts of the planet - a lot of tranatlantic flights cross Greenland, for example.
Originally posted by Blackmarketeer
Bravo, Oz, I for one am glad to see sanity and reasoning still have a place here on ATS.
Those satellite "before" and "after" views certainly drive home just how much air traffic, and their residual contrail/cirrus cloud formation, has increased in the last couple decades.
Now considering the amount of air traffic over Europe and North America, imagine the amount of sunlight being reflected back out into space. It would be an enormous amount.
Originally posted by Essan
reply to post by AllSeeingI
If you re-read my earlier post, you'll see that the current consensus of opinion amongst atmospheric scientists studying them is that contrails cause warming.
See also: www.co2offsetresearch.org...
Originally posted by OzWeatherman
reply to post by AllSeeingI
But they dont need to increase the time contrails last as they do that themselves. When the temperature and humidity is correct this will always occur.