Chinese weather experts say they have stopped the rain from falling in experiments, so their next big task will be to guarantee a dry opening ceremony at August’s Olympic Games. 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.

Recent Beijing Downpour

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

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

Ms 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, we use a coolant made from
liquid nitrogen to increase the number of droplets while decreasing
their mean size," she said.

"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."

China has long used weather manipulation to increase rainfall in the
parched north of the country, firing seeding agents into the clouds
using anti-aircraft guns.

This method might also be used to prevent wet weather at the stadium
by inducing the rain to fall before it reached the target area, said
Wang Yubin, deputy chief engineer at the bureau.

"Rain mitigation is a very complex process, though," he said.

The weather bureau is also working hard on preparing for one of the
pre-Games highlights, the ascent of the Olympic torch to the top of
Mount Everest.

"We will have very detailed forecasts," Mr Wang said. "We will be
able to tell the organisers: the winds are too strong, you cannot do it
on this day, or, you can do it on this day."

Via News.com.au