Air Pollution Alters Frequency And Intensity of Rainfall, Study Says

A new study says that air pollution can significantly alter the frequency and intensity of precipitation in a region, inhibiting the chances of light rain while exacerbating heavy storms in some cases. Using a decade of atmospheric data, U.S. scientists found that high levels of aerosols — including soot, dust and other particulate matter — can more than double the mean cloud height of deep convective clouds in comparison to clouds located in cleaner skies. While cloud drops forming around aerosol particles tend to be larger in cleaner air — and thus more likely to collide and form rain drops — in dirty air there are more and smaller drops, which tend to float and are slow to coalesce into rain drops. “The probability of heavy rain is virtually doubled from clean to dirty locations, while the chance of light rain is reduced by 50 percent,” said Zhanqing Li, a professor of atmospheric and oceanic science at the University of Maryland and lead author of the study, which is published in the journal Nature Geoscience.