China held a rain reduction drill in Hohhot Wednesday to ensure
that the opening and closing ceremonies of the Beijing Olympic
Games next year will not be interrupted by rain.
Three planes carrying 30 technicians flew for about 3 hours
within a 80 km-radius area about 8,000 meters high above Hohhot,
capital city of north China's Inner Mongolia Autonomous Region, spreading
silver iodide and 2,800 kg of diatomite into the clouds.
Although the clouds were not as thick as expected and other
weather conditions were unfavorable, the drill still collected
sufficient data, said Liu Xiaolin, official with the Inner Mongolia
weather control office.
The two types of catalyzer help to absorb vapor in the cloud and
prevent it from forming precipitation.
Apart from the commonly-used silver iodide, the
environment-friendly diatomite, a kind of white or gray-colored
mineral, was for the first time used in rain reduction in China,
and its effect is yet to be further studied, said Liu.
Rain reduction only works in a small area, and it would fail in
thick or large-scale clouds containing large amounts of water,
according to Liu.
The drill, overseen by weather authorities of Beijing and Inner
Mongolia, was just part of the rain reduction program to be
launched if needed next August, a month when Beijing is prone to
rain.
In addition to rain blocking above the venue area, cloud seeding
will be made between 15 km to 120 km away to induce rainfall before
it moves to the site of the event.
Rockets would be fired to disperse clouds in case of
thunderstorms and other weather conditions which are too risky for
piloted flights.
"We have done a good job in rainmaking, while more research and
practices are needed in rain reduction," said Liu.
Beijing has set up 26 bases around the city to carry out rain
reduction projects for the grand sports event next year.
The city has been trying to improve meteorological services to
serve the event, including accurate weather forecast and air
quality reports.
Liu denied suspects that the drill would worsen the drought
plaguing the western and middle Inner Mongolia recently, saying the
practice just temporarily suspend precipitation.
(Xinhua News Agency August 10, 2007)