Friday, September 9, 2011

Need Rain? Try Lasers

Desperate people have tried everything from firing cannons into the sky to lacing clouds with silver iodide. Now researchers have attempted to make it rain with lasers.

On the banks of the Rhone River in 2009 and 2010, Swiss researchers fired ultrashort pulses of a powerful mobile laser into the sky 28 different times. The laser shots created nanometer-sized particles in the air. These particles then allowed water molecules to bind together, forming droplets and avoiding re-evaporation.

The researchers reported their results in the online journal Nature Communications.

The droplets were too small to fall as rain, perhaps because the laser just wasn't strong enough or did not hit enough material in the sky. But the scientists note that their technique might also be used to prevent rain, by creating more of the smaller water droplets that stay airborne. And the laser system apparently works in temperatures ranging from 2 degrees Celsius up to 36 degrees C, though the laser bursts become less effective as it gets warmer.

Of course, this finding is preliminary. But, given crippling drought in Texas and catastrophic rains in Vermont, controlling the weather--especially rain--remains an attractive prospect for a laser light show.

View the original article here

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