Reluctant Lightning

Chronic curiosity led Benjamin Franklin to fly a kite into a thunderstorm-he got a mild shock and proof that lightning is electrical. A year later, a Russian professor tried the experiment and was killed by a bolt of lightning that passed through his head. Safely insulated scientists have tried to duplicate Franklin's trick, hopeful that they can learn to cause lightning at will. But by last week even the U.S. Department of Defense was convinced that it is no small stunt to lure lightning out of a passing cloud.

Still the scientists keep trying. Supported by the Navy and the National Science Foundation, Dr. Bernard Vonnegut of Arthur D. Little, Inc. has been trying for five years to hook up with significant amounts of atmospheric electricity. At first he tried flying tethered balloons into the base of thunderheads. Nothing much happened. A tiny spark jumped from the end of the mooring wire, but never a thunderbolt followed, not even when lightning was flashing all around. Apparently the wire drew ions out of the nearby parts of the cloud, thus insulating itself from full-scale lightning.

Last summer Dr. Vonnegut led an elaborate thunderstorm study near Socorro, N. Mex., where a stationary thundercloud forms almost every day above 10,300-ft Mount Withington. The scientists flew instrument-laden balloons into the handy cloud; they flew airplanes through it and over it. With a helicopter they strung thin wires between Mount Withington and neighboring peaks, and used them to inject electrical charges into clouds. Though they gathered valuable information about cloud electricity, none of their efforts made lightning strike when they wanted it.

But the high-voltage prize is too valuable for Dr. Vonnegut to quit. Next summer he and his frustrated Joves will return to Mount Withington armed with new apparatus, including giant bows and arrows, for firing fine wires high into lightning-charged clouds. The experiment, they point out, has an eminently practical purpose. Radar observation of thunderclouds has shown that lightning often precedes the formation of rain. Vonnegut suspects that the lightning creates vast numbers of charged particles that cause a cloud's small water droplets to attract one another and swell into drops large enough to fall as rain. If he can learn how to make lightning flash in a growing thunderhead, he may yet learn to coax rain from a cloud that would otherwise soar unproductively overhead.

This file is automatically generated by a robot program, so reader's discretion is required.