August 31, 2011
Powerful Laser Could One Day Help Make Rain
Researchers from the University of Geneva report they could soon be able to control when and where rain falls.
While ℠cloud seeding´ has existed for some time it is not considered a safe way of creating rain clouds because it involves filling the air with small particles of dry ice and silver iodide, meaning that along with raindrops falling from the sky, so would chemicals that have far-reaching implications on the environment.
But the new laser method is different. It uses natural humidity levels and atmospheric conditions to create water droplets.
“The laser can run continuously, you can aim it well, and you don't disperse huge amounts of silver iodide in the atmosphere,” physicist Jerome Kasparian, of the University of Geneva, told The Daily Mail.
“You can also turn the laser on and off at will, which makes it easier to assess whether it has any effect. When the Chinese launch silver iodide into the sky, it is very hard to know whether it would have rained anyway,” he told The Guardian.
The drops created -- each less than a thousandth of a millimeter across -- were nowhere near heavy enough to fall, but experts hope to eventually make them hundreds of times larger in order to create rainfall.
The method works by firing laser beams into the air, creating nitric acid particles which draw water molecules together and stop them from evaporating.
On the banks of the Rhone River, the researchers showcased the technique by constructing a gigantic mobile laser. They fired the beam of intense laser light into the atmosphere for 133 hours to produce the tiny droplets of water.
“Maybe one day this could be a way to attenuate the monsoon or reduce flooding in certain areas,” Kasparian added.
If the process is repeated in air currents that are blowing toward mountains, researchers believe the air would be cool enough to cause the droplets to grow large enough to fall as rain.
The researchers published their study in the Nature Communications journal.
On the Net: