NEW YORK Air pollution may have a silver lining
in some parts of the United States -- it might help make summer
weekends less rainy, according to a new study.
Scientists have long questioned whether particulate
pollution from vehicles and factories, which is higher during
the workweek, changes weather patterns.
The study, published on Thursday in the Journal of
Geophysical Research - Atmospheres, found that tiny particulate
matter from workweek pollution may "seed" summer clouds in the
U.S. Southeast, where plentiful hot, moist air tends to form
"There is a kind of a feedback loop," where pollution
causes heavier storms during the workweek that flush smog from
the atmosphere and tend to leave summer weekend weather clearer
and less rainy, said Thomas Bell, an atmospheric scientist at
NASA's Goddard Space Flight Center and the report's lead
"Pollution dies on the weekends, so you have the tendency
for less severe storms and nicer, clearer air," he said.
On average, it rains more in the Southeast between Tuesday
and Thursday than from Saturday through Monday, the NASA-funded
Its satellite data found that afternoon rainfall peaks on
Tuesday, with 1.8 times more rainfall than on Saturday, which
experiences the least amount of afternoon rain.
The pollution-rain connection was less pronounced in
western half of the country, where it tends to be drier in the
In cloud seeding, water and ice in clouds grab hold around
particles, forming additional water droplets that lead to
Bell said the study suggests that weather forecasters may
be able to sharpen their rain predictions by focusing more on
(Reporting by Timothy Gardner; Editing by Xavier Briand)