Ship exhaust provides cloud experiment.
Cloud experts have long suspected that small particles of pollution, called aerosols, could make clouds reflect more sunlight and thereby lower the surface temperature of the earth. Now, satellite images of the tracks of ship exhaust are providing the first evidence in support of this theory, says James A. Coakley of the National Center of Atmospheric Research in Boulder, Colo.
Although these aerosols on their own might absorb solar radiation, they cause the clouds to absorb less sunlight by serving as the nuclei for developing cloud droplets. In a contaminated cloud, aerosols increase the number of droplets but decrease the average size of the droplets--an effect that makes the clouds more reflective. The tracks of contaminated clouds then appear on satellite images at certain wavelengths, report Coakley and his colleagues in the Aug. 28 SCIENCE.
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|Title Annotation:||aerosols from ship exhaust make clouds reflect more sunlight|
|Date:||Sep 12, 1987|
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