Scientists hope lightning does strike twice

A team of European scientists has deliberately triggered electrical activity in thunderclouds for the first time by aiming high-power pulses of laser light into a thunderstorm.

Firing lasers into clouds to generate lighting may sound like comic book science, but it could reveal the secrets of thunderstorms

At the top of South Baldy Peak in New Mexico during two passing thunderstorms, the researchers used laser pulses to create small channels of ionised gas that can conduct electricity. No air-to-ground lightning was triggered because the filaments were too short-lived, but the laser pulses generated discharges in the thunderclouds themselves.

“This was an important first step toward triggering lightning strikes with laser beams,” says Jérôme Kasparian of the University of Lyon in France. “It was the first time we generated lighting precursors in a thundercloud.”

The next step of generating full-blown lightning strikes may come, he adds, after the team reprograms their lasers to use more sophisticated pulse sequences that will make longer-lived filaments to further conduct the lightning during storms.
The researchers say triggering lightning strikes is an important tool for basic and applied research because it enables researchers to study the mechanisms underlying lightning strikes. Triggered lightning strikes will also allow engineers to evaluate and test the lightning-sensitivity of airplanes and critical infrastructure such as power lines.

During the tests, the research team quantified the electrical activity in the clouds after discharging laser pulses. Statistical analysis showed that their laser pulses indeed enhanced the electrical activity in the thundercloud where it was aimed - in effect they generated small local discharges located at the position of the plasma channels.

The limitation of the experiment, though, was that they could not generate plasma channels that lived long enough to conduct lightning all the way to the ground. The plasma channels dissipated before the lightning could travel more than a few meters along them. The team is currently looking to increase the power of the laser pulses by a factor of 10 and use bursts of pulses to generate the plasmas much more efficiently.