Study: Cities make storms more intense

PRINCETON, N.J., Aug. 15 (UPI) -- A U.S. study has determined summer thunderstorms become much more intense when they collide with a city than when crossing open countryside.

Alexandros Ntelekos and James Smith of Princeton University's School of Engineering and Applied Science focused on an intense thunderstorm that hit Baltimore in July 2004.

Their modeling suggests the city experienced about 30 percent more rainfall than the area would have received had no buildings existed. The storm produced about six inches of rain within a two-hour period.

A storm of that intensity occurs only once every 200 years or so, but the researchers said they might become more frequent.

"Precipitation events like gully-washing rainstorms are expected to increase in intensity as the world warms due to the buildup of greenhouse gases," said Princeton Professor Michael Oppenheimer. "This is just the sort of research that combines science, engineering and social response that may allow us to better cope with the future, warmer climate.

"I hope it will also serve as a warning about the complexity of adaptation and, therefore, as a goad to policymakers to act more urgently to stabilize the climate."

The research appeared earlier this year in the Journal of Hydrometeorology.