LEARNING ABOUT LIGHTNING

UNIVERSITY OF FLORIDA RESEARCHERS ARE INTERNATIONAL LEADERS IN UNDERSTANDING ONE OF NATURE'S MOST POWERFUL FORCES

Lightning is capricious, short-lived and deadly, and researching the phenomenon is never easy. But earlier this year, it was maddening.

The state's worst drought in more than half a century made for perpetually clear spring nights at the University of Florida's International Center for Lightning Research and Testing at the Camp Blanding national guard base near Starke. By the time storms started blowing up in June, wildfires across the state had prompted state officials to forbid not only Fourth of July fireworks but also the rockets UF engineers fire to trigger lightning. Despite spending 12 hours a day at the center keeping equipment at the ready, the engineers could only watch and wait as storms blew over.

"It was a horror," says Martin Uman, chair of the College of Engineering's electrical and computer engineering department and an international expert in lightning. "We were all set to go, everybody was there."

Even in a normal summer, few natural phenomena pose as great a challenge to scientific inquiry as the study of lightning. It's random, it lasts less than a second and its birthplace in the clouds is impossibly hidden from view.

Despite the obstacles, however, engineers at the center and the Lightning Research Laboratory on the UF campus have made significant strides. Much of modern understanding of the physics of lightning can be attributed to the work of Uman and his colleagues. The researchers also have helped protect people and property from lightning's harmful reach.

It's difficult to turn one's eyes away from a lightning storm. The facts about it only increase the wonder. Lightning has a temperature in the air of 50,000 degrees. It makes the brightest light and the loudest sound in nature.

Meanwhile, it keeps jealous guard of some of its most vital secrets.

"Every time we try to do an experiment to look at one aspect of it, we discover something we never thought about," Uman says.

Triggered Lightning

At Camp Blanding a dirt road with a "Military Property No Trespassing" sign leads to an open gate and a mobile home, air conditioners humming in the midday heat.

Inside, Doug Jordan, an associate professor of electrical engineering at the University of West Florida, shows a visitor two large, high-speed cameras he uses for optical measurements.

Jordan, who has spent 20 years researching lightning's optical properties, is living proof of the difficulty of his subject. His doctoral dissertation was based entirely on an extraordinarily lucky series of observations made in a single afternoon. After 15 years photographing lightning, he guesses he has only 15 "really good images."

Engineers have long sought to corner their elusive quarry by triggering lightning using wire-trailing rockets.

At UF, engineers launch slender rockets from batteries of steel tubes 2,400 feet into storm clouds. Each rocket trails a thin, Kevlar-coated wire to conduct lightning back to the ground.

The method works, sometimes. Researchers say they still don't understand lightning well enough to pinpoint when a rocket will spur a strike. Each rocket, built on site for about $700, is a gamble. In a good summer, researchers fire 75 to 80 rockets and score 35 strikes.

"Some storms, everything looks right. You fire rockets and you can't get anything at all," said George Schnetzer, a consultant for Sandia National Laboratories. "Other storms, it's even questionable whether we should be shooting, and we get good results."

Lightning Landing Pad

At the far end of a sandy field at Camp Blanding is a 35-foot wood structure topped by a long lightning rod. Nearby lies a small airplane runway built nearly to scale.

Planes don't touch down on this runway, but lightning does.

Vladimir Rakov, a UF professor of electrical and computer engineering, explains that lightning is a major hazard at small, unstaffed airports because it knocks out runway lights.

If a pilot approaches the runway and can't turn on the lights by remote control, "what happens next depends on how much fuel the pilot has left," Rakov says.

Now in the second year of a project funded by the Florida Department of Transportation, researchers trigger lightning to the runway, built to Federal Aviation Administration standards, to better understand how it affects runway lighting systems.

"When we understand the mechanism, we will try to design a better lightning protection system," Rakov says.

The project is one of several aimed at saving lives and reducing property damage from lightning, which kills about 150 people annually in the United States and accounts for $500 million in insurance claims, most for damaged or destroyed electronics and computers.

The center also conducts research funded by the Electric Power Research Institute, a consortium of utility companies that founded the Camp Blanding facility in 1993 and donated it to UF in 1994.

Lightning Physics

Such "applied" research on practical lightning protection helps pay much of the bill for the "theoretical" research Uman says most interests the UF scientists: the physics of lightning.

At the same time they test runway lighting and other equipment, the engineers collect data to probe how lightning travels down from the sky, then connects with an upward discharge from the ground to cause its familiar blinding flash. The National Science Foundation helps fund this research.

"The lab probably has published 100 papers on different aspects of lightning," Uman says. "Mostly, it's about electric and magnetic fields and how they are related to currents."

Engineers' equipment is often highly specialized. Advances in optical and computer technologies in the past two decades have helped researchers dissect the lightning process, Uman says. A Japanese researcher with one of the world's fastest cameras photographed separate images of a lightning stroke every hundred nanoseconds, or every tenth of a millionth of a second.

Ewen Thomson, a UF associate professor of electrical and computer engineering, is one of the few lightning researchers who does not work at Camp Blanding. Instead, he has spent the past 10 years at the Kennedy Space Center using an advanced lightning detection system to gather and interpret data on how lightning forms in a cloud.

"Lightning lasts only about a half a second or so, and most of the lightning is in the cloud, which you can't see or photograph," Thomson says. "The distinctive feature about the system we're using, compared to others that locate lightning, is the interpretation of the physics."

Scientists have studied lightning since before Ben Franklin's famous kite-flying experiment, but one of the most significant advances came with the development of technology to locate lightning, an achievement Uman shares with University of Arizona colleagues Phillip Krider and Burt Pifer.

Lightning emits radio signals, and in the early 1970s Uman and the other two researchers developed a method of determining lightning's source by gathering radio signals from multiple sources and triangulating them.

"It was an application of direction finding that had been done on airplanes and ships from fixed transmitters but never worked on lightning because the lightning signal was too complex," Uman says.

Today, the technology is central to the U.S. National Lightning Detection Network, which pinpoints strikes in this country and Canada. The National Weather Service, Federal Aviation Administration and about 100 electric utility companies use data from the network. So does The Weather Channel, as viewers familiar with the cable channel's hourly lightning updates can testify.

Researchers are uncovering more and more ways to use the technology to identify and track weather patterns, he adds.

"For instance, now it's known that when the lightning in the storm turns from negative to predominantly positive, the sign of the charge being lowered, the storm is almost over," Uman said.

Evolving knowledge about the usefulness of lightning in weather prediction demonstrates how much remains to be learned about this mysterious and fascinating phenomenon.

With one of the world's premier lightning research facilities, UF engineers will likely be at the forefront of discovery.

"Every year we're able to do fancier and fancier stuff and learn more and more than we could before," Uman says.

Martin Uman
Professor and Chair, Department of Electrical and
Computer Engineering,
(352) 392-0913, muman@admin.ee.ufl.edu

Vladimir Rakov
Professor, Department of Electrical and Computer Engineering,
(352) 392-4242, rakov@admin.ee.ufl.edu

Ewen Thomson
Associate Professor, Department of Electrical and Computer Engineering,
(352) 392-9753, ethom@ece.ufl.edu

Related web site:
http://www.eel.ufl.edu/~lightning/

Sidebar:

Art Meets Science

Lightning cuts through the air in a microsecond, but when it hits the ground it sometimes leaves a glassy trail of fused sand that can last centuries.

To some, these "fulgurites" look like pieces of dirty glass. But to electrical engineers, fulgurites are lightning's tangible legacy, delicate pieces of "fossilized lightning" that require painstaking excavation to reveal.

And to renowned artist Allan McCollum, the objects are a metaphor for natural and human creativity.

In the summer of 1997, researchers at UF's International Center for Lightning Research and Testing worked with McCollum, an internationally acclaimed contemporary artist, to create fulgurites that will be the centerpiece of an exhibit that debuts this fall in Tampa.

Before the project, engineers at the center regarded fulgurites as something of a curiosity, once spending weeks excavating a 17-foot-long fulgurite recognized by the Guinness Book of World Records as the longest ever. But in an illustration of how science and art can intertwine in ways that enrich scientists and artists alike, the project drew their scholarly attention to the objects -- and taught them a few things along the way.

"I think it heightened our interest in fulgurites, which are of practical interest because they go to underground power lines and communication lines," says Professor Martin Uman, director of the lightning center and chair of UF's Department of Electrical and Computer Engineering.

Fulgurites have long fascinated people, but, until McCollum, no one had experimented with making the objects above ground with triggered lightning.

McCollum, 54, has exhibited in the Museum of Modern Art and Whitney Museum of American Art in New York, and two years ago his work appeared with a collection of American sculptures in an exhibit at the White House. In recent years, his work has examined the crossover between art and science. He chanced upon an article about Uman's research in Discover magazine and began researching the topic.

Two years ago, a vacation in Sarasota presented a unique opportunity: Margaret Miller, director of the University of South Florida Contemporary Art Museum, asked McCollum if he would be interested in a collaborative project for USF and the Museum of Science and Industry in Tampa. When he mentioned his interest in fulgurites, Miller arranged a meeting for McCollum with Uman.

As it happens, Uman studied art in college and paints as a hobby. He embraced the project, which the Museum of Science and Industry agreed to underwrite with $10,000 from a combination of city, state and county grants for the lab's costs for rockets and other expenses.

So in the summer of 1997, McCollum and Jade Dellinger, an independent curator and co-coordinator of the project, moved into a motel room in Starke and began visiting the lightning lab every day.

McCollum suggested that the researchers try to create the fulgurites above ground -- an idea embraced by Dan Cordier, an experienced fossil excavator who has helped excavate several fulgurites on the site.

Cordier filled PVC tubes with different minerals, all of which could be found in the sand at the site, something important to McCollum's artistic goals. To ensure the lightning penetrated the minerals, Cordier ran a thin wire through the pipes, then connected it to the 35-foot lightning tower. Rockets launched from the tower trail a thin wire intended to provide a conducting path for the lightning to strike back to Earth.

Over the course of a few weeks, a handful of strikes gave Cordier and the artists a look at how fulgurites formed in different minerals. Zircon proved McCollum's favorite.

"It was very evident very quickly that zircon made a very beautiful, precise kind of regularly swirled fulgurite," McCollum says.

But the trailing-wire method creates open-ended fulgurites, and McCollum sought a fulgurite with closed ends because he intended to reproduce many copies, and closed-end figures are cheaper and easier to reproduce. At Uman's suggestion, Cordier decided to try arcing electricity between two electrodes.

"Martin suggested we try the old Frankenstein electrode approach," Cordier says.

Cordier and McCollum placed zircon in a red trash receptacle sandwiched between two electrodes, then connected a wire from the rocket directly to the electrodes. A storm blew up, and McCollum pressed the "fire" button. Another researcher, meanwhile, used a camera capable of shooting 500 frames per second to record the event.

The small fulgurite resembling a bone that resulted pleased McCollum and perplexed the engineers, who anticipated he would prefer a more complex figure with lots of branches, wild colors or other unique characteristics.

Science, as well as art, benefited from the project.

"Every strike we get that has fulgurites, we learn something new," Cordier says. "Probably the biggest thing we learned from working with Allan - which we didn't know and hadn't given any consideration to - is that clays seem to inhibit fulgurite formation."

Today, fulgurites are merely a scientific curiosity, but with their unique optical properties they may one day prove useful to the electronics industry or in other applications, Cordier says.

McCollum says he gained a fresh perspective from working with the engineers, and vice versa. For example, other engineers began experimenting with making fulgurites using such materials as marbles.

"I think there was just a sort of natural curiosity about another person's way of seeing, so each person comes away with a new way of looking at their own discipline," McCollum says.

A company in Sanford, Fla. that uses sand to create tourist souvenirs is producing 10,000 copies of the fulgurite for the McCollum exhibit, set to debut at the USF Contemporary Art Museum on October 23 in connection with a simultaneous exhibit and presentation on the project at the Museum of Science and Industry.

While the installation's final "look" is still evolving, McCollum says, "I think I'm going to build a very large table and just sort of pile the fulgurites on top in a heap."

The installation exhibit will be accompanied by small booklets that discuss lightning and how fulgurites are created, McCollum says, adding that he hopes to use the exhibit and booklets to convey a message about inspiration and creation.

"I wanted to make an object that ... suggested instant creating, almost the way an artist creates, or the way the universe creates."

Related web site:
http://arts.usf.edu/museum/allan.html