Seed solution: China to keep nature from raining on Asian Games

Feeling confident after recent successful attempts to control rainfall in the country, China is planning to seed clouds around the 16^th Asian Games next year with chemicals that will keep it from raining on its parade, or at least the games' opening and closing ceremonies.

LIQUIDATING RAIN: China plans to use liquid nitrogen, dry ice and silver iodide to disperse rain clouds headed toward Guangdong Olympic Stadium during the 2010 Asian Game's opening and closing ceremonies.

Even though the November 2010 games to be held in Guangzhou's 80,000-seat Guangdong Olympic Stadium will take place during southern China's supposed dry season, the Olympic Council of Asia, the continent's main sports governing body, announced earlier this week that liquid nitrogen, dry ice and silver iodide will be used to all but eliminate any chance of precipitation.

All three cooling agents can be used to either induce or suppress precipitation, depending on the amount that is administered and the condition of the clouds. In the case of China, they are likely planning to use smaller amounts of each agent in an effort to cool any moisture in clouds headed for the stadium, forming smaller ice particles that would evaporate before they hit the ground, says Dan Kottlowski, an expert senior meteorologist with weather forecasting service AccuWeather. Dry ice (which is solid carbon dioxide) is often used to flash freeze food, and silver iodide (a chemical sometimes used in antiseptics) has molecular structure very similar to that of ice, allowing the substance to induce freezing when introduced to clouds. Liquid nitrogen is a cryogenic fluid at around –320 degrees Fahrenheit that can cause rapid freezing on contact with living tissue, which is why it's sometimes used to remove skin lesions such as warts.

Most cloud seeding around the world aims at increasing precipitation or suppressing hail, says Joe Golden, a retired senior meteorologist for the National Oceanic and Atmospheric Administration (NOAA). While it is well known that you can overseed, possibly diminishing the chance of precipitation.

Chinese officials claim to have performed "successful rain elimination" during the 2008 Olympics held in Beijing, according to the council.

Russia has likewise been known to attempt to overseed clouds to prevent rain from spoiling outdoor activities in Moscow. Reports indicate last summer the Russian Air Force dropped a bag of cement through the roof of a residential home while trying to keep weather from interfering with celebration of the country's June 12 holiday. The bag was supposed to pulverise in the sky, letting loose cement particles to seed the cloud.

(Larry Greenemeier)