New Technique Aims High-Energy Laser Beams into the Clouds to Create Rain

Ever think that technology may one day advance enough so that humans could control the weather? That day may already be here. Researchers are developing a new technique to aim a high-energy laser beam into the clouds in order to make it rain or trigger lightning.

The idea isn't as farfetched as you might think. Water condensation and lightning activity in clouds are linked to large amounts of static charged particles. Stimulating those particles with the right kind of laser can potentially summon rain showers when they're needed.

That's not to say that this technique has been actually been seen in action. More work is needed before it's a viable method for weather control. The current idea is that researchers will surround the laser beam with a second beam to act as an energy reservoir. This sustains the central beam to greater distances than previously possible. The second beam can refuel and help prevent the dissipation of the primary beam.

When a laser beam becomes intense enough, it actually behaves differently. It collapses inward on itself and this collapse can become so intense that the electrons in the air's oxygen and nitrogen are ripped off and create plasma. This plasma then tries to spread the beam back out, and creates a struggle, called filamentation, between the spread and collapsing of an ultra-short laser pulse. The filamentation creates a filament that propagates until the properties of air cause the beam to disperse.

"Because a filament creates excited electrons in its wake as it moves, it artificially seeds the conditions necessary for rain and lightning to occur," said Matthew Mills, one of the researchers, in a news release. "What would be nice is to have a sneaky way which allows us to produce an arbitrary long 'filament extension cable.' It turns out that if you wrap a large, low intensity, doughnut-like 'dress' beam around the filament and slowly move it inward, you can provide this arbitrary extension."

The findings reveal that in the future, it may be possible to induce rain and lightning. That's not all, though; the new method could also be used in long-distance sensors and spectrometers to identify chemical makeup.

The findings are published in the journal Nature Photonics.