To prevent rain over the roofless Olympic stadium that Beijing, the city's branch of the national Weather Modification Office (a department of the larger China Meteorological Administration) has prepared a three-stage program for the Olympics.
First, they will track the region's weather via satellites, planes, radar, and an IBM p575 supercomputer, purchased from Big Blue (9.8 trillion floating point ops. per/s). It models 44,000 square kilometers accurately enough to generate hourly forecasts for each kilometer.
Second, using aircraft and an array of twenty artillery and rocket-launch sites around Beijing, they will shoot and spray silver iodide and dry ice into incoming clouds so the rain can be flushed out before they hit the stadium.
then, any heavy clouds near the stadium will be seeded with chemicals to shrink droplets so that rain won't fall until those clouds have passed over. Zhang Qian said "We use a coolant made from liquid nitrogen to increase the number of droplets while decreasing their average size. As a result, the smaller droplets are less likely to fall, and precipitation can be reduced." August is part of Northeast Asia's rainy season; chances of precipitation over Beijing on any day that month will approach 50 percent. Still, while tests with clouds bearing heavy rain loads haven't always been successful, Qian claims that "the results with light rain have been satisfactory."
Although they possess the world's largest weather modification program, the Chinese point to the Russians as being the most advanced. In 1986, Russian scientists deployed cloud-seeding measures to prevent radioactive rain from Chernobyl from reaching Moscow, and in 2000 they cleared clouds before an anniversary ceremony commemorating the end of World War II; China's then president, Jiang Zemin, witnessed the results firsthand and pushed to adopt the same approach back home. As for the historical credit for starting the whole weather-engineering ball rolling back in 1946, that belongs to employees of General Electric in Schenectady, NY--most notably, scientist Bernard Vonnegut (brother of the late novelist Kurt), who worked out silver iodide's potential to provide crystals around which cloud moisture would condense. During the 1960s and '70s, the United States invested millions of federal dollars in experiments like Stormfury (aimed at hurricane control), Skywater (aimed at snow- and rainfall increase), and Skyfire (aimed at lightning suppression). Simultaneously, the U.S. military tried to use weather modification as a weapon in Project Popeye, during the Vietnam War, by rain-making over the Ho Chi Minh Trail in an effort to close it.