By Duncan Geere, Wired UK

Artificial rainmaking is an imprecise, environmentally-hazardous process, but it could be made a little more eco-friendly with the addition of lasers.

A team from the University of Geneva has used a mobile laser laboratory to trigger the formation of water droplets in the air — a step towards being able to create rain. During 113 hours of firings, the cloud physicists discovered that pulses of laser light create nitric acid particles in the air, which serve as condensation nuclei for droplets.

Those droplets only grew to a few micrometers in size — too small to overcome air turbulence and fall out under the influence of gravity as rain. Typically, droplets need to be around a tenth of a millimeter to begin to fall. However, the effect of the lasers is significant enough for the physicists to pursue the work further.

Current cloud seeding methods tend to involve chemicals like silver iodide, which is classified as a hazardous substance and as a toxic pollutant. Ingestion in large enough quantities can cause iodism, which manifests as skin rashes, headaches, anemia, irritation of mucous membranes and depression. Chucking that stuff into the atmosphere isn’t a great idea.

Laser-assisted rainmaking has other benefits too. “You can also turn the laser on and off at will, which makes it easier to assess whether it has any effect,” says Jérôme Kasparian from the University of Geneva. “When the Chinese launch silver iodide into the sky, it is very hard to know whether it would have rained anyway.”

The research was reported in Nature Communications.

Image: Ack Ook/Flickr

Source: Wired.co.uk

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