BEIJING - Chance of showers during the 2008 Beijing Olympics: 50 percent. But Chinese meteorologists have a plan to bring sunshine.

The meteorologists say they can force rain in the days before the Olympics, through a process known as cloud-seeding, to clean the air and ensure clear skies.

China has been tinkering with artificial rainmaking for decades. Whether it works is a subject of scientific debate.

Weather patterns for the last 30 years indicate there is a 50 percent chance of rain for both the opening ceremony Aug. 8 and the closing ceremony two weeks later, said Wang Yubin, an engineer with the Beijing Meteorological Bureau.

The forced rain also could help clean Beijing's polluted air, said Wang Jianjie, another meteorologist with the bureau.

"When conditions permit, we will artificially increase rainfall," she said. "Rainfall is a way to naturally clean the air."

In 2003, the U.S. National Academy of Sciences questioned the science behind cloud-seeding as "too weak." China, however, frequently uses artificial rainmaking in the drought-plagued north.

Last May, Beijing boasted of having generated rainfall to clear the air and streets after the worst dust storm in a decade.

Technicians with the Beijing Weather Modification Office said they fired seven rocket shells containing 163 cigarette-size sticks of silver iodide over the city's skies. They said it provoked a chemical reaction in clouds that forced four-tenths of an inch of rain.

Beijing's air pollution is among Asia's worst. Officials have shuttered several chemical and steel plants on the city's edge, and many polluters will shut down - or cut back - during the Olympics.

But the city also has 2.9 million registered vehicles - and the number is expected to reach 3.3 million by the Olympics.