Lasers That Stoke the clouds

Ben Franklin had his kites. Jerome Kasparian has his laser – what he and his colleagues hope will become the latest tool in studying lightning and its effects.

Using a powerful, mobile laser on a New Mexico mountaintop, the team sent laser pulses into two thunderheads and triggered electrical discharges.

With improvements, the researchers say, the technique could replace small rockets that trail thin wires as lightning triggers. The rocket-based approach has been used to explore a range of phenomenon – from the physics of lightning itself to the direct and indirect effects it can have on technologies ranging from airliners to power lines. But rockets are expensive and inefficient, averaging one strike for every two launches.

The laser pulses set up strands of hot, electrically charged gas within the cloud. These plasma strands serve as electrical conductors. Based on data from instruments that can monitor a storm's electrical activity, the researchers were able to trigger mini lightning bolts. But the conducting strands did not last long enough for the discharges to travel more than a few yards. The team, based at universities in France and Germany, reported its results in the current issue of Optics Express, an online publication of the Optical Society of America.