Attempts to modify the weather can be dangerous. They require pilots to head into the kind of clouds they would normally avoid. But officials claim that China’s efforts to trigger or boost precipitation by scattering chemicals in the sky, which began in the 1950s, have been hugely successful. Today the country spends at least $200m a year on the programme. In 2018 about 50,000 people were involved in it, most of them part-time or seasonal staff working from small offices in rural areas.

Among the 50 or so countries where cloud-seeding is practiced, China is the most enthusiastic promoter of it….Officials claim it can help to put out wildfires and reduce air pollution. State media report that cloud-seeding brings down about 50bn cubic metres of extra rain or snow across the country each year—equal to about 8% of total water demand. Officials in Beijing claim that in the parched capital, seeding can boost rainfall by 15%…

Recent advances in radar and computer modelling have made rigorous tests more possible. Scientists now generally agree that cloud-seeding can slightly augment snowfall from specific types of cloud that form on the slopes of mountains. Some of China’s weather-modification projects take place in such environments. But elsewhere, despite the lack of convincing proof that it works, farmers still want the government to try. And the government likes getting credit when rain does fall. Cloud-seeding creates employment in poor rural places, in particular for army veterans who believe that the government owes them a job.

Only a few of China’s rainmakers use planes. More commonly, they fire silver iodide into the sky from artillery pieces. But that can be dangerous, too. Locals are often advised to keep an eye out for unexploded shells, which occasionally land on people’s homes….

Excerpts from No silver lining: Cloud-seeding will not solve China’s water shortages, Economist, Mar. 27, 2021