Laser Triggers Lightning "Precursors" in Clouds

Rebecca Carroll
for National Geographic News
April 16, 2008

Scientists say they have triggered early stages of lightning by shooting lasers into clouds over New Mexico.

The apparent breakthrough brings the decades-old goal of causing lightning with lasers closer, according to a new study.

"This was an important first step," said Jérôme Kasparian of the University of Geneva, lead author of the study.

"What we observed were kind of precursors of lightning."

If achieved, lightning control could eventually make airports, power plants, and other sites safer, scientists say.

If bolts could be conveniently triggered, the controlled strikes might deplete storm clouds of charged particles that naturally initiate the bolts—possibly preventing uncontrolled and dangerous lightning around sensitive areas.

Affordable and reliable laser-triggered lightning would also be a boon to scientists who study the still largely mysterious phenomenon (lightning facts).

Rocket Science First

Lightning occurs when storm clouds separate negative and positive electrical charge (interactive guide to lightning).

In cloud-to-ground lightning (see photos), a "leader" starts in the cloud, sending a hot, negative charge downward. If the electrical field on the ground is strong enough, a positive charge rises up to meet the leader, completing an electrical circuit that is visible as a lightning bolt.

Scientists can already trigger lightning with rockets. But the process is cumbersome and only works about half of the time, according to Joseph Dwyer, a professor of physics and space sciences at the Florida Institute of Technology who was not involved in the study.

Typically, Kevlar-coated copper wire coils are attached to rockets that are launched into storm clouds.

Continued on Next Page >>


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