Jet Contrails Impact on the Radiation Budget

Contrails (condensation trails) from jet aircraft represent man-made clouds in the lower stratosphere that can have the same effect on the radiation budget as natural clouds. Stratospheric clouds generally reflect solar radiation during the day but contribute to trapping of long-wave radiation both day and night. The net effect is that they lead to slightly cooler daytime temperature and warmer nighttime temperatures, in other words they reduce the diurnal temperature range (DTR - difference between the daytime high temperature and the nighttime low temperature). Travis et al (2002) seized on the opportunity presented by the grounding of all US aircraft from 11-14 September 2001 to see whether the DTR would increase without contrails. They found the DTR was 1 degree C above the 30-year average for this three year period, adding evidence that jet aircraft do have an impact on the radiation budget over the US.

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