BEIJING — As they prepare to host the Olympics — an event whose very purpose is to push the limits of human beings — the Chinese are trying to do what man never has: Control the weather.

With five months to go before the Summer Games come to Beijing, Chinese scientists say they are confident they can keep rain away from the opening ceremony, or summon a storm on cue to clear the city's choking pollution.

It's a bold — and, according to international scientists, dubious — bit of stage managing, even for a nation that has already shown an outsize ambition to use the Olympics to showcase its development from rural poverty to economic powerhouse.

China is spending $40 billion to remake the infrastructure of the ancient capital, and it already spends an estimated $100 million a year and employs 50,000 for rainmaking.

At installations like one called Fragrant Hills, outside Beijing, peasants don military fatigues and helmets and squat behind anti-aircraft guns and rocket launchers, blasting the sky with silver iodide, hoping to shock rain from the clouds.

If rain threatens the opening or closing ceremony, Beijing officials say they will set up several banks of rocket launchers outside the city to seed threatening clouds and cause them to release their rain before it reaches the capital.

"We are now drafting the implementation plan for the artificial rain mitigation for the opening and closing ceremonies," said Wang Yubin, a Beijing Meteorological Bureau engineer. "This is a very complex process, so we must select the right time and place."

China, short on water and arable land, has lavished some of the scarce resources it has on rainmaking and rain prevention.

The Chinese scientists say it worked — increasing rainfall during those years by 210 billion cubic meters, enough to meet the annual needs of 400 million people. China has a population of about 1.3 billion.

Other scientists are not so sure.

"I don't think their chances of preventing rain are very high at all," said Dr. Roelof Bruintjes, a meteorologist with the U.S. National Center for Atmospheric Research, who was in China several weeks ago and told Chinese scientists he was skeptical.