Feb. 1, 2008 -- China, which is preparing to host the 2008 Summer Olympics in Beijing, has taken on a task that would flummox even Hurcules: controlling the weather.
Determined to prevent rain from dampening the spirits -- not to mention the crowds -- on opening day ceremonies, the government plans to seed any threatening clouds with chemicals to dispel, or at least delay, rainfall.
Though it sounds like a classroom assignment from Hogwarts School of Witchcraft and Wizardry, weather modification programs have been around for more than 50 years. California and 10 western states in the United States regularly lace clouds with various substances to increase snow and rain, though the practice has not passed full scientific muster.
The problem is there are too many factors that affect the weather, making naturally occurring phenomena difficult to separate from man-made triggers.
Not that people haven't tried.
Roscoe Braham, who pioneered weather modification experiments at the University of Chicago in the 1950s, always believed it would be possible to change the weather, but years and years of tests were inconclusive.
"It was unfortunate," Braham said in an interview with Discovery News from his retirement home in North Carolina. "There was no strong scientific base for changing the weather."
"The atmosphere and nature are so broad and so big and the best efforts that man can put forth are really small in that respect," added Braham, who now serves as Scholar-in-Residence for North Carolina State University's Department of Marine, Earth and Atmospheric Sciences.
"If (proof) exists, we're looking for a rather small needle in a huge haystack of hay. You don't even know what it looks like, you don't even know what success would be," he said.
That's not to say the techniques were disproved, either.
A March 2007 study for the California Energy Commission by the U.S. Bureau of Reclamation found that cloud-seeding programs statewide produced 300,000 to 400,000 acre-feet of water annually.
The water, mostly in the form of melted snow, benefits agriculture and the state's hydroelectric power industry. It also augments recreational and municipal supplies.
To make or mitigate rain, target clouds are injected with chemicals such as silver iodide, which has a crystalline structure almost identical to ice, or with dry ice, which changes the clouds' structure.
Braham recalls watching the transformation take place from aboard research aircraft.
"Dry ice is most effective. You just crush it up and spew it out. A hole will develop in the cloud," within about 10 minutes, Braham said. "It's always mesmerizing to see this change."
The chemical transforms water droplets, which cause a cloud's opacity, into ice crystals. That leaves a clear patch which, over time, fills in.
As for China's Olympic feat, Braham said it would be nice if the experiment was run and published prior to the big day so it could be weighed on its scientific merits. Otherwise, he, for one, would award the gold medal for weather to Mother Nature.
Related Links:
Irene Klotz's blog: Space Diary
Larry O'Hanlon's blog: Earth Impacts