He says that two-thirds of China’s almost 3,000 counties have tried artificial methods to induce more rainfall, sometimes resulting in lawsuits over rights to mine passing clouds for water. Such efforts, Zheng reports, have involved some 6,533 cannons, 5,939 rocket launchers, and numerous aircraft in an attempt to seed clouds across one-third of China’s landmass with dry ice, ammonia, and silver iodide.