LUOHE, China – When rare clouds appear over this often-parched agricultural region, workers at the local weather bureau routinely roll out anti-aircraft guns and blast away at the sky.
The shells that explode contain fine particles of silver iodide, which scatter through the moisture-laden clouds. If all goes well, a rainstorm occurs.
"You feel rain drops almost immediately," said Xu Zeming, a vendor of veterinary medicine in the nearby town of Shuzhuangxiang.
In this Northern Plains region, where about half of China's wheat and corn grows and peach orchards blossom, drought is an ever-looming threat. Nine of the last 10 years have brought below-average rainfall. So farmers praise the weather bureau's rainmakers as local heroes.
China is the world's leading cloud seeder, using an array of methods to disperse chemicals into cloud layers, including specialized aircraft, rockets, artillery shells, balloons and even mountaintop dispersing devices.
But as in the days of yore, when legend says that emperors ordered underlings to toss virgin girls into rivers to please the water dragon and unleash rainstorms, the quest for rain carries with it the threat of tempest. Some local officials now grumble that upwind neighbors unfairly intercept clouds for seeding, depriving downwind areas of rainfall.
Moreover, recent heavy rains and floods across China have raised questions about whether fiddling with weather can bring calamity as well as fortune.
"The technique is not perfect. There are many scientific problems," said Hu Zhijin, an adviser to the Institute of Weather Modification at the China Meteorological Administration in Beijing.
Nonetheless, China spent about $49 million nationwide on cloud-seeding efforts last year. Some 35,000 people took part in rainmaking efforts, employing 6,929 anti-aircraft guns and 3,804 rocket and artillery launchers to fire chemicals into the clouds, said the nation's top meteorological official, Qin Dahe, in a February report.
Qin said rainmaking efforts receive "a high level of importance in China and have played a very remarkable role" in reducing the impact of drought on the economy.
Some officials said cloud seeding has increased rainfall perhaps by 10 percent.
"A fairly small amount of precipitation over a huge area brings a huge quantity of water – several hundred million tons," Hu said.
A non-government expert, however, said the benefits of cloud seeding – while less costly than building canals or treating recycled water – are unproved.
"It's a last-ditch effort. This provides some relief. Whether it is real relief or psychological relief, it shows that the government is doing something," said Michael Ma, author of the 2004 book, "China's Water Crisis."
The accusation of "rain theft" arose in Henan province, in central China, after a heavy rainstorm in mid-July broke a long drought. To induce the rain, weather technicians in five cities and surrounding counties fired thousands of canisters of silver iodide into the atmosphere.
But rainfall was vastly unequal.
"The peasants in the rural areas were wild with joy, while the urban residents complained about the traffic difficulties due to too much water," a regional newspaper, the Big River News, reported.
While the cities of Pingdingshan, Xuchang, Zhumadian and Luohe got nearly 4 inches of rain, Zhoukou got barely a quarter as much. Only a mist fell in some surrounding areas.
Zhoukou officials, requesting anonymity, complained to the Big River News and the national Xinhua news agency that the neighboring cities had milked the cloud system nearly dry before it arrived in their area. Municipal officials later demanded legislation to regulate how to divvy up the clouds.
National officials in China demur at arbitrating artificially induced rainfall.
"Atmospheric systems are very large. They may cover several provinces. How to seed them and get the benefit is not such a small-scale issue," said Hu, the scientist.
The issue apparently is touchy. Provincial officials repeatedly refused, or cut short, interviews with a journalist touring Henan province. They also prohibited photographs of the anti-aircraft guns used to seed clouds.
Given the severity of water scarcity in northern China, such sensitivity isn't surprising. In a large part of northern China, annual rainfall has decreased significantly in the past two decades, while population has soared. Rivers run dry at certain times of year. Beijing, the capital, is sinking at a rate of about 4 inches a year as it depletes the water table below.
Compounding the problem is inefficient water usage. Last year, for each $1,205 of economic output (gross domestic product), China consumed four times more water than the world average, and five to 10 times more water than such developed countries as the United States.
To quench thirsty regions of China, authorities began a $55 billion project to divert 12 trillion gallons a year from the Yangtze River northward.
While cloud seeding is routinely done in 24 countries, including on a very limited scale in some U.S. states, the congressionally mandated National Research Council said in an October report that science still hasn't proved that seeding clouds works.
Chinese officials, though, said they have no doubt.
"We have basically solved the drought problem," Kong Dezhi, the deputy director of the Zhoukou Meteorological Bureau, said before ushering a visitor out of her office.
She didn't make clear whether the resolved drought was around her city, or a downwind area.