Weather modification: The rain makers

Whether it is the Chinese firing weapons into the sky to make it rain, or the Thai government setting up a "royal rainmaking project", the science of weather modification has always had a touch of the sci-fi about it. So it is perhaps little surprise that the effectiveness of such an eccentric area of research has always been a little foggy. Indeed, no matter how hard you try – say, through launching silver-iodide particles into clouds to make them rain – it's hard to tell how influential you're actually being as it might have happened anyway.

But now, one of the world's leading weather experts thinks that the wind surrounding weather modification is set to change. Roelof Bruintjes, of the National Center for Atmospheric Research in Colorado, USA, believes that weather-monitoring technology is so hot nowadays that science fiction may soon become science fact. Speaking earlier this week, he said: "Now we can measure clouds so well – even from the inside – we can get many more answers as to what the effects of man-made intervention are, and separate them from what would have happened naturally.
"For the first time, we can discover whether humans have changed weather patterns. It's a whole new opportunity. We are at the most exciting time for weather modification in its history."

Many of the world's driest nations have dabbled in weather modification since its first major lab breakthrough in 1949, when researchers at General Electric in New York discovered that silver-iodide smoke caused the kind of droplets in clouds to turn to ice, a process vital to rain formation. Since then, however, experts came to the conclusion that the processes involved in rain formation were just too complex.

But that hasn't stopped many governments from trying. There are currently 150 weather-modification projects taking place in more than 40 countries. In many of these, researchers are using trials in which some randomly chosen clouds are "seeded" while others are not, and both groups are monitored. Arlen Huggins of the Desert Research Institute in Nevada, USA, is leading one of these studies in Australia's Snowy Mountains, where the snow pack has shrunk in recent decades. Reportedly, their results to date might suggest that seeding works (although there are still two years of the six-year project left to go).

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