Beijing said to have some success preventing rain

By Nick Mulvenney

BEIJING (Reuters) - Beijing has successfully managed to stop light rainfall in experiments aimed at guaranteeing a dry opening ceremony at August's Olympic Games, officials said on Wednesday.

With no roof on the showpiece Bird's Nest stadium, the Beijing Meteorological Bureau has been charged with developing methods of preventing wet weather spoiling what promises to be a spectacular start to the Games on the evening of August 8.

"Our experiments with rain mitigation have been aimed at light rain," Zhang Qian, head of weather manipulation at the bureau, told a news conference.

"With heavy rain it is more difficult. The results with light rain have been satisfactory."

Qian said different strategies were used to stop rain on different types of clouds, but both had proved not to harm the environment.

"For cold clouds below zero degrees (Celcius), we use a coolant made from liquid nitrogen to increase the number of droplets while decreasing their mean size," she added.

"As a result, the smaller droplets are less likely to fall and precipitation can be reduced.

"For clouds above zero degrees we use the seeding agent silver iodide to accelerate the droplets' collision and coalescence, producing a downdraft which suppresses the formation of clouds."