Chinese Rainmakers Competing for Clouds
Such science is widely known, he said, and was applied in the United States and elsewhere as early as the 1950s. But because of its severe weather problems, China has put the know-how to practical use more often than other countries in recent decades. So far, he added, no signs have emerged that frequent cloud seeding harms the environment, but scientists are keeping an eye out.
As the practice spread, the Chinese central government in March 2002 handed down a directive regulating weather modification. Mainly, it mandated cooperation and information-sharing by provinces, counties and cities, and barred cloud seeding by unofficial groups.
The director of the Weather Modification Bureau in Jilin province, north of Beijing, said his staff files an annual cloud-seeding plan in line with the directive, but that the clouds' mobility and the uneven distribution of water vapor within them make the enterprise unpredictable at best. Nevertheless, he said, his office frequently is in touch with neighboring provinces on cloud-seeding plans in the area, along the North Korean border.
"Sometimes we even have combined action with them," said the official, who insisted on being identified only as Zheng. "Although the effect would be great if several provinces work together when there is a huge cloud system in the sky, in reality, we seldom do that."
Nanjing and five other cities in Jiangsu province, 550 miles southeast of Beijing, organized joint cloud seeding on July 25, producing a much-needed rain during a hot spell, and another round has been planned for this week. The operation was designed mainly to save electricity, which also is scarce, by bringing down temperatures and easing pressure from air conditioner use.
"The purpose was to cool down the cities," Bai Kawa, director of the Jiangsu provincial Weather Modification Office, said in a telephone conversation. "The hot weather has been going on for days. We launched rockets to seed the clouds. The result was satisfying."
Hu said his years of research have showed that even the best efforts of China's rainmakers produce only a 10 percent or 15 percent increase in rainfall. In addition, he said, the vagaries of nature, such as wind direction and velocity, mean the effect of cloud seeding on any given locality is difficult to predict.
Yiwu City, south of Shanghai in Zhejiang province bordering the South China Sea, has been forced to cut electricity and water supplies to sweltering residents every other day this summer, city officials said. Seeking to alleviate the situation, its meteorologists tried to seed the clouds 10 times during May and June, with mixed results.
An official with the weather bureau said the meteorologists succeeded in bringing down one heavy rain. But in a dry July, as temperatures have risen even higher, the sky has been uniformly blue, making further cloud seeding impossible, said the official, who declined to be identified.
The shortages also have produced tugging among regions and cities on water resources other than rain. Beijing and Tianjin, a large port city 80 miles to the southwest, are competing for water from the Juhe River, the China Youth Daily reported last week. Meanwhile, the central government has begun work on a huge canal designed to push water from southern rivers to the parched north -- a plan that has not made everybody in the south happy.
Researcher Zhang Jing contributed to this report.
© 2004 The Washington Post Company
In China's northeast province of Liaoning, recurrent drought can turn the wheat crop brittle. The Weather Modification Bureau there has salted clouds about twice a month this year.
(2001 Photo Ng Han Guan -- AP)