CHINESE emperors were once thought by their subjects able to make it
rain with their prayers. Chinese
officials today
put more trust in
science. They are boosting spending on what they call the world\''s
largest programme of artificial rainmaking. Its effects, however, are
not much easier to quantify.（1）Just as grateful subjects praised the heavens for any rain that
fell, the state-controlled media in China often report on the heroic
contributions made by "weather-modification offices" whenever needed
rain comes. These offices, set up over the past 15 years, deploy
artillery, rocket-launchers and aeroplanes to seed clouds with
chemicals （usually silver iodide） that encourage droplets to form and
fall where needed, or prevent the formation of destructive hailstones. China\''s efforts have been encouraged by an increasingly desperate
shortage of water in the north. China also frets about the Olympic
games in Beijing in August 2008, in a season when rainstorms are
common. Making it rain away from big events is a key area of research.
（2）Last week
officials awarded merit certificates to organisations
involved in "weather guarantee" work for a summit with African leaders
held in Beijing in November. Those honoured included the air force,
Beijing\''s military command and the Second Artillery, which controls
missiles. All were urged to do a good job at an Olympic rehearsal next
year. Artificial rainmaking is practised in many countries but its success
is hard to prove. In recent years, China has been helped by big
improvements in its weather-monitoring capacity. Its latest satellite,
Fengyun-2D, was launched on December 8th with Olympic forecasting as a
priority mission. It plans to launch another 22 weather satellites by
2020.