Lesser countries might wish for clear weather on an important day. China makes it happen. Last month Chinese officials announced that they will work to ensure that the skies remain bright during the opening and closing ceremonies of the Olympics this August, tracking clouds in the days leading up to the ceremonies and, if any threaten to deliver an untimely shower, forcing the rain to fall early.
There's nothing new about cloud-seeding, which has been around since the 1940s. Scientists at General Electric discovered that dropping dry ice into a cloud could help droplets too small to fall freeze into tiny clumps, forming heavier drops. Today weather modifiers often use silver iodide to create a similar effect.
Cloud-seeding is not practiced much in the U.S. anymore, as scientists have concluded that it doesn't work reliably. But don't tell the Chinese. The country has by far the biggest weather-modification service in the world, reportedly with 7,000 antiaircraft guns and 4,900 rocket launchers that can fire chemicals into the sky.
Mao Zedong once said, "Man must control nature." But environmental hubris is visible in such things as China's dirty skies and the 1,000 sq. mi. (2,590 sq km) of territory it loses to desertification every year. Whether or not Beijing can ensure a sunny Olympics, the state of the nation demonstrates that you mess with nature at your peril.