By Sid Perkins
Trends seen in meteorological data gathered on a Chinese mountaintop suggest that air pollution reduces the amount of precipitation that falls at high-altitude sites.
When winds force moisture-laden air masses up a mountainside, the air cools, its water vapor condenses, and precipitation often results. Therefore, many mountainous locales receive more rainfall and snow than do sites on the plains just upwind, says Daniel Rosenfeld, an atmospheric scientist at the Hebrew University of Jerusalem.