"Understanding interactions among clouds, aerosols and precipitation is one of the grand challenges for climate research in the decade ahead," says Tony Busalacchi, a scientist at the University of Maryland and chair of the Joint Scientific Committee of the World Climate Research Program.
"Findings from this study are a significant advance in our understanding of such processes, with implications for both climate science and sustainable development," says Busalacchi.
"We have known for a long time that aerosols impact both the heating and phase changes [such as condensing and freezing] of clouds, and that they can either inhibit or intensify clouds and precipitation," says Russell Dickerson, an atmospheric scientist at the University of Maryland.
"What we have not been able to determine until now is the net effect," says Dickerson. "This study shows that fine particulate matter, mostly from air pollution, impedes gentle rains while exacerbating severe storms. It adds urgency to the need to control sulfur, nitrogen and hydrocarbon emissions."
According to Steve Ghan of the Pacific Northwest National Laboratory, "This work confirms what previous cloud modeling studies had suggested: that although clouds are influenced by many factors, increasing aerosols enhances the variability of precipitation, suppressing it when precipitation is light and intensifying it when it is strong.
"This complex influence is completely missing from climate models, casting doubt on their ability to simulate the response of precipitation to changes in aerosol pollution."
Aerosols are tiny solid particles or liquid particles suspended in air. They include soot, dust and sulfate particles and are what we commonly think of when we talk about air pollution.
Aerosols come, for example, from the combustion of fossil fuels, from industrial and agricultur
|Contact: Cheryl Dybas|
National Science Foundation