China's Air Pollution Decreasing Light Rainfall, Study Finds

beijing rain photo

Though overall rainfall has increased, the frequency with which rain falls has declined. Photo: Egor via flickr.

And you thought air pollution was just about respiratory illnesses... New research indicates that China's air pollution has decreased the amount of light rainfall in the nation over the past 50 years -- the number of rainy days decreasing 23% in the eastern part of the country. Decreasing this pollution could ease ongoing drought: The study, done by the Department of Energy's Pacific Northwest National Laboratory and published in the latest issue of the Journal of Geophysical Research - Atmospheres, shows that though overall rainfall in parts of the eastern portion of China has actually increased, light rainfall has decreased. At the same time, sulphur pollution from fossil fuels has increased nine times.

More Aerosols = Smaller Water Droplets, Fewer Rainclouds
As to why this is happening, Science Daily explains:

Cloud droplets form around aerosols, so the team determined the concentration of cloud droplets over China. They found higher concentrations of droplets when more aerosols were present. But more droplets mean that each cloud droplet is smaller, in the same way that filling 10 ice cream cones from a quart of ice cream results in smaller scoops than if the same amount were put in only five cones.

In polluted areas the water drops are up to 50% smaller than in non-polluted. These smaller drops have a harder time forming rain-producing clouds, leading to a decrease in light rainfall.

More: Science Daily
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