Science has progressed substantially in the 250 years since Benjamin Franklin's experiments with lightning. Today, when scientists at the University of Florida want to study lightning, they stand in a carefully insulated trailer and launch a rocket towards a thundercloud to induce an artificial lightning bolt.

"We trigger between 30 and 50 lightning discharges every summer, says Dr. Vladimir Rakov, one of the leading lightning researchers in the United States. Dr. Rakov does his research at Camp Blanding, located midway between Jacksonville and Gainesville, in central Florida, an area known as "lightning alley."

"Natural lightning is virtually impossible to study," says Dr. Rakov, "because you have to know where it is going to strike and try to place your instruments at that point." One alternative is to create an artificial lightning strike in the laboratory, but this is difficult, expensive, and does not fully reflect the reality of natural lightning.

Another alternative is to induce lightning from passing thunderclouds. The most effective technique for triggering lightning involves launching a small rocket trailing a thin grounded wire toward a charged cloud overhead. The rockets used at Camp Blanding are about three feet long, and are fitted with a special spool carrying Kevlar-reinforced copper wire. This wire, connected to a designated strike point on the ground, extends down as the rocket rises towards the thundercloud. "This is equivalent to erecting a tall thin structure," Dr. Rakov explains. "The wire distorts the electrical field under the cloud, and if the conditions are right, there will be a lightning discharge."

"It is a dangerous operation," says Dr. Rakov. "Sometimes lightning does not behave well. Sometimes it deflects from the path as defined by the wire, and strikes elsewhere." No one is allowed outside during the tests, and all work is conducted from a special metallic trailer that is fully grounded and designed to protect the scientists from "anomalous discharges." No metallic wires enter the trailer, only pneumatic tubes and fiber optic cables to link the scientists with their rockets and testing instruments. "Why? Because lightning can travel along metallic wires, and get to you inside the shelter."

The rockets usually travel 200 or 300 yards (600 or 900 feet) into the air before being struck by lightning. The lightning strikes the tip of the rocket and immediately vaporizes the trailing copper wire, leaving a plasma channel hovering in midair, which carries the current down to the grounding point.

Clustered around the strike zone are a range of instruments and detectors that measure the size of the current, the power of the sound waves, and the brilliance of the flash. Dr. Rakov and his colleagues also test a variety of industrial devices to determine their ability to withstand a strike: devices like surge protectors, electric lines, airport runway lights, golf course shelters, even the insulation on airplanes and nuclear weapons. Lightning does about one billion dollars in damage to power lines and electrical appliances in the United States each year, and kills about 85 people annually.

"As our society becomes increasingly technological with computers and sensitive electronics," says Dr. Rakov, "it becomes increasingly vulnerable to lightning strikes. Our job is try to understand how lightning works, so we can figure out new ways to protect ourselves."