Last week, Beijing was suffering from rising temperatures, sand sweeping down from the Gobi Desert and high levels of pollution caused by 2.5 million cars and the reconstruction of the city for the 2008 Olympic Games, reported The Australian (31 May 2006 p8). Suddenly, on Friday evening, a rainstorm emerged, apparently from nowhere.
Rainmaker rocketry: In fact, it was "rocket rain". For its true genesis lay in shells fired by technicians of the Beijing Weather Modification Office. They contained cigarette-sized sticks of silver iodide, which produce ice crystals when seeded within moist clouds, and turn to rain as they fall to warmer air.
Temporary relief: The skies then cleared, producing a miraculously fine Sunday. The city’s 15 million or so inhabitants, enduring the worst drought in northern China for 50 years, applauded.
Sealed city surfaces isolate water table: But a water technology expert said on 30 May that the impact of a single downpour on Beijing’s steadily dwindling water table would only be marginal, because of the extent to which the city’s surfaces are compacted by building works and new roads. The result is that most of the rainwater evaporates before it can find open, receptive ground into which to sink.
50b tonne annual raindance: China and Thailand are the major users of artificial rain. In China’s new five-year plan, it says it will create 50 billion tonnes of rain every year, deploying greatly increased resources into rain-making research, which it began in 1958.
Giving Mother Nature a hand: Throughout the country, 23 of the 34 provinces have established weather modification bureaus like Beijing’s, which use dozens of aircraft and several thousand anti-aircraft guns, as well as about 4000 rocket launchers, to seed clouds with iodine to produce rain. Chinese meteorologists say such efforts can only increase rainfall by 10-15 per cent at best, however. And without cloud cover, the weather modification artillerymen can do nothing.
The Australian, 31/5/2006, p. 8
Source: Erisk Net