HERTFORDSHIRE, England, June 22 (UPI) -- To understand climate change, scientists must understand a seemingly infinite number of variables. Depending on their shape, size and altitude, clouds can have both a cooling and warming effect on the atmosphere.
When skies are clear, clouds made by airplanes and the effluent they expel into the sky -- called contrails -- aren't thought to have much of an effect on the atmosphere. But new research suggests contrails magnify the reflectivity of an already cloudy sky.