Q: Can China control the weather through cloud seeding? A: Sort of. China has invested heavily in a process known as cloud seeding, using more than 12,000 anti-aircraft guns, rocket launchers and planes to launch pellets containing silver iodide into clouds. Silver iodide is thought to concentrate moisture and cause rain.

Every year, China launches thousands of rockets and artillery shells into the sky. They're not part of a set of war games or preparation for a battle with Taiwan, but rather a battle with the weather. Through its Weather Modification Program, the Chinese government hopes to control the fickle forces behind rain. Run by the Weather Modification Department, a division of the Chinese Academy of Meteorological Science, the program employs and trains 32,000 to 35,000 people across China, some of them farmers, who are paid $100 a month to handle anti-aircraft guns and rocket launchers.

The heavy weapons are used to launch pellets containing silver iodide into clouds. Silver iodide is thought to concentrate moisture and cause rain. The process is known as cloud seeding and China has invested heavily in it, using more than 12,000 anti-aircraft guns and rocket launchers in addition to about 30 planes [Source: Asia Times Online].

Chinese research into weather control began in 1958, when the practice was still in its early stages. With a population of more than 1.3 billion, China requires vast amounts of water. Cities like Beijing suffer from terrible smog, and rain can help clear away air pollution. The government is using cloud seeding to try to produce rain for farmers, stave off drought and fill water basins.

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So how does it work? Even in areas with very low humidity, water is present in the sky and in clouds. A rainstorm happens after moisture collects around particles in the air, causing it to reach a level of saturation at which point it can no longer hold in that moisture. Cloud seeding essentially helps that process along, providing "nuclei" around which water condenses. These nuclei can be salts, calcium chloride, dry ice or silver iodide, which the Chinese use. Silver iodide is used because its form is similar to ice crystals. Calcium chloride is often used in warm or tropical areas.

Cloud seeding is heavily used in northern China, an area that does not receive much rain -- its rainfall levels are 35 percent below the world average, and some of its water supplies are significantly polluted. Zhiang Qiang, who runs the Beijing Weather Modification Office, told the Asia Times that water levels in Beijing's water basins have increased up to 13 percent due to cloud seeding [Source: Asia Times Online]. Cloud seeding has also been used to cool down Beijing on hot days.

The Beijing Weather Modification Office is researching how to prevent rain in the city on Aug. 8, 2008, during the opening ceremonies of the 2008 Summer Olympics. The government has even guaranteed clear skies for the event. They plan to do it by tracking cloud formations and causing rain in the days leading up to the ceremonies. However, one official admits that although cloud seeding could be effective in preventing light rain on Aug. 8, it could not curb the onset of a moderate to heavy storm.

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­Scientists aren't sure if cloud seeding actually works, but despite the skepticism, China is moving forward, spending $60 to $90 million a year on weather modification, in addition to the $266 million spent from 1995 to 2003 [Source:Things Asian]. The government plans to produce 50 billion cubic meters of rain a year through the practice [Source: Asia Times Online].

­China has a re­putation for launching ambitious projects, from the Great Wall in ancient times to the highest railroad in the world, connecting Qinghai to Tibet­. But is the investment in cloud seeding worth it, and can the government really make it rain whenever it sees the need? On the next page, we'll look at some of the methods and criticism of cloud seeding.

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