Scientists in Florida are attempting to control one of nature’s strongest and most unpredictable forces by firing rockets into thunderclouds — the real-world equivalent of creating lightning in a bottle.
As dark clouds gathered over central Florida, a small team of scientists frantically ran about the ground below, checking that their equipment was ready to go. As the first rumbles of thunder began to vibrate the air, a look at the instruments indicated that the electric tension of the air was closing in on 5,000 volts. It was time.
Shortly afterward, they fired a rocket. It shot into the sky, dragging a Kevlar-coated copper wire behind it. For a few seconds, they could only stare intently at the launcher, but then: boom. Electric tension heated the air, which expanded, creating a pressure wave of sound. Everything lit up as lightning whistled down. Everybody cheered.
“When we fire a rocket and everything works, there’s great jubilation — it’s like landing a spacecraft on Mars,” says Martin Uman, a lightning scientist at the University of Florida’s International Center for Lightning Research and Testing. The center is located in an area of the United States known as Lightning Alley, where the humid, warm summers produce countless thunderstorms, and where each square mile is hit by lightning an average of 12 times a year.
But despite the frequent strikes, we still know little about lightning. How can we study something so momentary? It’s not like anyone can predict where lightning will strike, and even if scientists were to stand, fully equipped, right in the middle of a storm, there’s no guarantee that lightning would strike close enough for them to be able to measure it. Not to mention that such an attempt would be extremely dangerous.
Lightning hunters gamble with their lives, so Uman and his colleagues have changed the rules of the game. They trigger lightning and have it strike in the middle of an army of sensors. For the first time, science has mastered lightning, and researchers are finally beginning to answer questions that have puzzled them for almost 100 years.
Scientists since the 1930s have surmised that lightning produces X-rays, but they have had no way to test the theory. Until now. The UF scientists, using special cameras, dissected lightning and confirmed that X-rays accompany the strikes, but made a surprising discovery:
The temperature of the lightning is only a fraction of what is normally required to create X-rays. So the lightning itself doesn’t emit X-rays, and yet X-rays are emitted every time lightning moves forward.
If scientists can begin to understand why this happens, it may help them solve the mystery of how lightning proliferates — and, ultimately, how to predict the location of the next lightning strike.
“In one summer, we were basically able to confirm what had taken people 70 years of studying natural lightning,” says Joe Dwyer, another project scientist.
A physics professor at the Florida Institute of Technology and a leading lightning expert, he is enthusiastic about the new opportunities. “What is surprising is that though people have been interested in lightning since Benjamin Franklin’s kite experiment 250 years ago, it’s really taking off right now,” he says.
The lightning experiments are being conducted at the former military base of Camp Blanding, where more than 100 instruments have been installed in the area to record every detail of a lightning strike. The equipment measures the electrical field (an area surrounded by electrically charged particles) and the magnetic field, as well as radiation, lightning voltage, the strength of the sound waves and how powerful the flash is. The scientists are able to trigger lightning 15 to 30 times a year — after firing at least twice as many rockets, at a price of more than $700 apiece. But whether or not a thunderstorm will produce lightning is still just an educated guess. “If we wait for all the conditions to be perfect, that still only works about half of the time,” Uman says.
Big gains, but still a long road
In principle, the rocket controls the lightning, but given the unpredictability of natural forces, being outside during the experiments is strictly prohibited. Instead, the scientists position themselves inside lightning-proof trailers. The rocket is launched using compressed air, and all communication takes place via fiber-optic cables, because the metal in ordinary cables can conduct lightning from the strike site to the trailer.
In the 1960s, American scientists began to trigger lightning for the first time, by firing rockets from a ship. The method was refined in the mid-’70s, but the scientific work only began to truly gather speed over the past 10 to 15 years.
Although researchers have learned much in a short time, our knowledge of lightning is still superficial. But lightning strikes are responsible for thousands of deaths and billions of dollars worth of damage every year, so scientists still must answer the big questions: How does lightning start? How does it propagate through the air? And what causes it to strike a given area or object?
The Florida results are the first step toward being able to protect homes, power lines and airports from strikes, as well as controlling where lightning will strike and avoiding it.
Uman has a hopeful view: “Fifty years from now, I think we will be able to predict where and when lightning strikes.”