No time to be under a cloud

Hitting every detail, China says it may control tomorrow's weather

BEIJING - In an effort to fully orchestrate the glittering pageantry of tomorrow night's Olympic opening ceremonies, the Chinese are trying to control Mother Nature and clear the skies overhead.

From driving restrictions designed to reduce pollution to meticulously manicured grounds throughout the city, little has been left to chance. And during a packed press conference yesterday at the Beijing International Media Center, that thoroughness was on full display as the country's top meteorologists discussed weather forecasting and weather modification for more than an hour.

"We can say we have already mastered the available rain reduction technologies in the world," said the director of China's Meteorological Administration, Yu Xinwen, through a translator. "We have invited experts from Russia to give us guidance on this aspect. To do a good job in this aspect, we need exploration and time. . . . Will we try it in the run-up to the Olympic Games? That will be determined by the weather and the needs of sport events."

The forecast calls for partly cloudy skies and temperatures in the mid-70s. If all goes as predicted, neither rain nor hazy pollution will ruin the show. If not, the Chinese cloud physicists may resort to seeding clouds with chemicals to alter rain patterns before the ceremony, then herald relatively clear skies as a scientific triumph.

The world's cloud physicists fear the Chinese will credit cloud seeding with clearing the skies. But China's ambitious plans for Olympic weather modification fall more into the realm of science fiction than science.

"I shake my head because this has brought about all sorts of controversy in weather modification," said physicist Roelof Bruintjes, who leads the weather modification programs at the National Center for Atmospheric Research in Boulder, Colo. "Many people are making unsubstantiated claims. The Russians have been doing cloud seeding on the May Day parades also, and like many people who do it, they dip into it with no scientific proof it works."

With recent smog-filled days blurring views of the National "Bird's Nest" Stadium and scattered thunderstorms originally forecast for the remainder of this week, Chinese meteorologists face even more obstacles to success. Leading up to the Olympics, the Chinese conducted cloud seeding experiments and developed a two-pronged weather modification plan. They would create rain to wash out pollution in areas away from Olympic venues. They would also prevent rain around the National Stadium to provide a perfect backdrop for the ceremonies.

Pressed several times for specifics, Yu did not elaborate on the technology. Cloud seeding, long used in dry areas to bring on rain, involves injecting silver iodide into clouds using rockets, artillery shells, or planes. The iodide disperses into the clouds and forms ice crystals. The ice crystals change into rain drops and fall from the clouds. But since cloud structure varies greatly depending on temperature, humidity, and pollution levels, there is no guarantee it will work in Beijing.

The Chinese also believe they can prevent rain by overloading clouds with iodide and ice crystals. With ice crystals competing for limited water vapor in the clouds, the crystals will be too small to fall as rain.

But this process is hypothetical, with no scientific evidence it will work. Experts in cloud seeding are skeptical potential Chinese efforts will make any difference during the Olympics.

"The problem is that the weather systems they have in Beijing are too large and too complex," said Zev Levin, professor emeritus of atmospheric physics at Tel Aviv University.

"It's like you're putting a fly on an elephant," said Levin, who has studied cloud seeding for 40 years. "The elephant doesn't even feel it, and he does what he wants to do based on his strength and his size. It is the same thing with the clouds. They are much too big. Anything the Chinese are trying to do in them will hardly make any dent in what the clouds are going to do naturally."

Scientists have explored the potential benefits of cloud seeding since the mid-1940s. But not until recent technological advances could atmosphere physicists gather precise data about the structure of clouds before and after seeding. Yu acknowledged the country's forecasting abilities are "still somewhat behind the international advanced level with room for improvement."

China did not begin upgrading its cloud seeding technology until five years ago. But more than scientific know-how may be at issue.

"China has spent a lot of money and a lot of years on cloud seeding," said Bruintjes. "They have 30,000 people working in this field. They have always been telling the government that it works. Maybe the government has never asked for scientific evidence. In those situations, if you do it for 30 years, suddenly telling your government it doesn't work may put you all out of a job. There's political issues involved, especially in a country like that. Deep down the scientists I have worked with in China know they need to really start evaluating and looking into what they are doing and trying to quantify it."

The Chinese cannot escape the facts, and the visible haze that settled on top of the city Sunday has remained. All the positive talk about the "Green Olympics" by Chinese officials at the heavily air-conditioned press conference was a marked contrast to the muggy, hazy air outside. Like claims about their ability to modify weather, specialists say, the Chinese overstate the impact of cloud seeding on pollution.

"It's a very superficial way of dealing with a problem that has roots that are much deeper," said Guy Brasseur, atmospheric chemist and pollution specialist at the National Center for Atmospheric Research. "If you can make rain, you can probably improve certain aspects of the pollution, but the improvement is going to be intermittent and limited in time and space."

Yu had a different perspective. He did concede China's meteorologists will face many challenges in the weeks ahead with rain, pollution, and weather modification. The threat of thunderstorms throughout most of the games only adds difficulty.

"You are all very concerned about weather modification," said Yu. "I can tell you it will be very effective with systematic weather. But when we encounter extreme weather conditions it will be very difficult for us to achieve remarkable results."

As much as the Chinese want to control human nature and mother nature during the Beijing Games, they say they may not achieve the impossible. They can revoke visas and send human rights protesters home, but the rain and haze may be here to stay.