NASA - National Aeronautics and Space Administration

One of the most visible anthropogenic phenomena in the atmosphere is the occurrence of contrails. The direct effects of contrails on surface temperature are investigated on the basis of the data sets for the cloud cover and surface temperature over the conterminous United States for the period 1971 – 2001. It is shown that the increase of the average daily temperature range (DTR) over the United States during the three-day grounding period of 11 – 14 September 2001 cannot be attributed to the absence of contrails, a subject was debated in several previous studies. The present analysis suggests that the DTR is attributed to the change of low cloudiness.