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Published: August 2012

Chasing Lightning

Chasing Lightning

“Tim Samaras has a storm in his headlights and the world’s fastest high-resolution camera in the trailer behind. Can it catch lightning in the act?

By George Johnson
Photograph by Carsten Peter

It’s a good thing there’s a rumble strip running along the shoulder, because Tim Samaras can’t keep his eyes on the road. It’s summer, and he’s driving a big, black Denali pickup pockmarked by hail and pulling a 16-foot trailer outfitted with high-speed cameras and other electronic gear. A laptop computer is mounted inside the cab to the right of the driver’s seat, and with one hand on the steering wheel and the other on a trackball, Samaras is mousing his way around a weather radar map of the Oklahoma Panhandle. A blob of colors—red in the middle surrounded like an oil slick by orange, yellow, green, and blue—shows a thunderstorm forming northeast of Boise City.

“It’s starting to spit out some pretty good lightning,” he says, looking at the little yellow crosses popping up on the radar. He glances again at the laptop, where another window is tracking our position with GPS. Then comes the buzzing of his tires against the rumble strip, and he calmly steers the rolling laboratory back onto the road.

With bugs splashing onto the windshield and a spiderweb of cracks—more old hail damage—gradually growing wider, we pass through Boise City, following the storm east toward Guymon. Ahead of us clouds are boiling up like cauliflower, the classic sign of the warm, moist updrafts that separate negatively charged water droplets and ice particles from positive ones (no one knows exactly how), creating multimillion-volt potentials—like the one that just exploded in the sky ahead of us.

“Did you just see that strike?” Samaras exclaims. Then comes another, and another. He’s got a pair of reading glasses dangling from his mouth, which he puts on to look at the radar, then swipes off to glance at the road. “See how that storm is anchored right there? That’s what we want.”

The flashes are coming every few seconds now, and the truck is hitting the rumble strip again and again. But just as he’s looking for a place to pull over, the blob on the radar starts shrinking. Samaras picks up speed, but by the time we reach Guymon, 60 miles down the road, the sun has appeared, and a rainbow is arcing overhead.

“Whenever you see the rainbow, it’s game over,” he says. “It’s a goner. I can’t believe it.” But at 6 p.m. his day is just beginning. The radar shows another blob forming over southern Kansas, 80 miles away.

Late summer is thunderstorm season in this part of the country, and since 2006 Samaras has been trying to do the impossible: capture an image of a lightning strike the moment it is born. The process typically begins when a descending zigzag of negatively charged electricity—a stepped leader—feels its way from cloud to ground. When it gets near enough, positive fingers of charge reach up from the earth. The instant the two come together, a dazzling surge of current—some 30,000 amps traveling at a third of the speed of light—leaps toward the sky. The burst of light from this “return stroke” is what you see with the naked eye, which often interprets the motion as downward. From beginning to end, the entire process takes as little as 200 milliseconds.

In Samaras’s trailer there are two Phantoms, high-speed cameras capable of shooting 10,000 frames per second. They have allowed him to capture stunning slow-motion videos detailing the paths of downward stepped leaders and occasionally the upward streamers. But as soon as the two connect—initiating an event called the attachment process—the flash from the return stroke blinds the camera, obliterating the details. Scientists would love to peek behind the curtain and watch the event as it unfolds, with the return stroke lifting off like a rocket from the ground.

Lying within the imagery might be clues to some of lightning’s biggest mysteries. Why will a lightning bolt sometimes strike a low tree when right beside it is a tall metal tower? And why, for that matter, does lightning strike at all? For all their intensity, the voltages produced in thunderclouds are not nearly strong enough to overcome the insulating properties of air. Some extra factor is required, and a picture of the attachment process might suggest an answer. Opening this frontier calls for a custom-outfitted camera capable of shooting more than a million high-resolution frames per second. There’s just one camera like that, and it too is in Samaras’s trailer.

Weighing 1,600 pounds and standing six feet high, the camera is a relic of the Cold War, originally used to film aboveground nuclear tests. Samaras first laid eyes on it in 1980, when he was working as a technician at the University of Denver Research Institute. The massive instrument was a marvel of analog technology. Light entering its main lens would strike a three-sided mirror, which sat at the center of a turbine driven by compressed air or, for really high speeds, helium. Rotating as fast as 6,000 revolutions per second, the mirror swept the light across the lenses of 82 35-millimeter film cameras, mounted shoulder to shoulder around the rim. The result was a sequence of images less than one-millionth of a second apart.

Samaras’s job involved studying conventional explosions, and he became the behemoth’s keeper, learning its idiosyncrasies, catering to its whims. Twenty-five years later, when he heard that the camera was being auctioned as government surplus, he placed a bid and bought it for $600—a hair above the price for aluminum scrap. Its proper name is a Beckman & Whitley 192. Samaras calls it the Kahuna.

With the help of funding from National Geographic, he retrofitted the beast, replacing the film technology with extremely sensitive digital sensors designed for deep-space exploration and adding specially tailored software and circuitry. But no matter how you modify it, an instrument weighing close to a ton has obvious drawbacks. In addition to its lack of maneuverability, the astoundingly fast Kahuna is in another sense very slow. Each time you want to take an ultra-high-speed shot, you have to wait about ten seconds for the turbine to spin up to speed. Then you have about a minute before you have to spin it down so it doesn’t overheat. If you’ve been lucky enough to capture an image, it will take a full 20 minutes to download the 1.8 gigabytes of data to see what you’ve got. Only then can you recock the trigger and try again.

In other words, Samaras will need a stationary storm that is producing lightning again and again, right where the camera is pointing. Some people rate his chances of success at close to zero. There are research facilities where he could reduce at least some of the variables by deploying the Kahuna on lightning triggered by firing rockets into storm clouds. But Samaras is dismissive of manufactured lightning—only the wild type will do.

He is used to having people tell him that what he’s trying can’t be done. Before he became obsessed with lightning, he spent several years chasing after tornadoes. He had designed electronic probes, mounted with video cameras and other instruments, to lay down in the likely path of a tornado so he could record what it looks and feels like from the inside. People were dubious about that too, but he managed to gather some of the most accurate readings ever of wind speed, barometric pressure, temperature, humidity—the ingredients that when mixed just so erupt into a devastating funnel of wind.

With hopes of catching up to the storm, we pass through Liberal, Kansas, and then head straight north toward Sublette. A dark mass of clouds is building over the plains. As the sun sets, the tops of the clouds cool. That means more uplift, more separation between negatively and positively charged particles, and more lightning. By the time we pull to the side of the road, the storm has become so violent that in the distance it has spawned a small tornado. The twister quickly dissipates, leaving a spectacular lightning show. Two long bolts crisscross the sky like an electrified X, followed by a barrage of ground strikes. Samaras starts up a gasoline generator, and the equipment inside the trailer comes alive. A wall of video screens displays weather information, and an electronic voice—the Lightning Lady, I call her—matter-of-factly announces the distance of the strikes: “17 miles, 15 miles, 11 miles.” Then she gives a warning: “Very high electric field.”

“The electric-field meter is going absolutely nuts,” Samaras observes. A sensor mounted on the shell of the trailer measures the charge of the atmosphere at ten kilovolts per meter and rising, meaning that it’s dangerous to be outside. The two Phantoms aboard the trailer go to work, capturing images of the milliseconds before and during the lightning flashes. Thunder is cracking above us. But throughout the cacophony, the Kahuna sits quietly off-line. The conditions just aren’t right for getting the shot.

We pack up and move on, and soon another rainbow—a double one—appears. Samaras stops the truck in the middle of the main intersection of Clayton, New Mexico, oblivious to the honks and cursing drivers, while the National Geographic photographer takes some pictures, of the ordinary kind.

On Labor Day weekend, toward the end of the season, I caught up with Samaras at an exit off I-25 in Belen, New Mexico. By then he and his crew had driven more than 10,000 miles across six states, collecting hundreds of megabytes of data from the Phantoms—but only near misses with the Kahuna.

With only two days left in the summer’s expedition, we followed a battery of storms north of the Magdalena Mountains. In midafternoon we found ourselves parked, purely by coincidence, directly across Highway 60 from the turnoff to the Langmuir Laboratory for Atmospheric Research—a premier spot for studying rocket-triggered lightning. A storm hung suspended over the mountains as if posed for a portrait, sparking lightning obediently above a distant ridge. Standing in the foreground on the other side of the highway, a cow gave us a curious eye. Using the animal as a reference point, Samaras started up the turbine and took aim. The sky flashed, the Kahuna fired, and the long download of data began.

Then, with the camera off-line, there was a better strike—this one directly over the cow. Unsure of the first shot, Samaras made a split-second decision to terminate the download and try again. The chance never came. He’ll never know whether that first attempt captured an image of the attachment process or just a blurry silhouette of a cow.

By the time I saw Samaras again, two years later, he had reluctantly decided to try what he felt in his heart was cheating: aiming his camera at rocket-triggered lightning. With a new pickup truck and an improved Kahuna—he had stayed home the previous summer jiggering the electronics—he and his crew had spent another two weeks following storms across the Southwest. Now he was making the long, slow climb to Langmuir’s mountaintop laboratory.

Built in 1963 by the New Mexico Institute of Mining and Technology in Socorro, the laboratory sits in the path of the monsoonal moisture that flows up each summer from the south. Sheltered inside an underground bunker called the Kiva, on South Baldy peak, a researcher remotely fires rockets, each connected to a long wire, into a highly charged storm cloud. Colleagues record the strike with a Phantom and other instruments in a building called the Annex, a mile away.

Bill Winn, head of the lab, seemed as skeptical about Samaras’s approach as Samaras was of triggered lightning. (“Isn’t he just interested in pretty pictures?” Winn had asked me earlier.) But the two men greeted each other cordially.

“You should have been here today,” Winn said. “We had three strikes.”

“Figures,” Samaras said. One of the scientists explained that when conditions were right, a rocket would be armed and a five-second countdown would begin—any longer and the storm might produce a natural flash out of range of their instruments. Samaras looked worried. Since the Kahuna took ten seconds to spin up to speed, he would have to idle the turbine at a loping pace to keep it from overheating, then crank it up before the countdown began.

The next day’s weather was discouragingly calm, but the storm that arose on the third day justified the wait. By early afternoon seven red-centered blobs were registering on the radar—a potent weather system to our northeast headed right for us. By 3 p.m. rain was falling faster and faster, hardening briefly to hail. We retreated inside the trailer and watched out the back. Thunder, lightning—then the radio call: “Kiva is arming rockets.” One storm had a purple center now, the most intense. Bands of red and orange were passing in front of us.

While the Langmuir crew watched from the safety of the Annex, I huddled on the trailer floor, shifting my attention between the weather outside and its abstraction on the radar. Wind was rocking us back and forth. If it hadn’t been for the anchor provided by the Kahuna, I thought the trailer might blow off the mountain. With another crack of the radio, the Kiva requested a launch window, and Samaras began idling the turbine. Then, “Kiva launch in five.” He ramped up the speed, and in the sky above us a rocket fired, its long, trailing wire instantly vaporized by lightning. But it happened too quickly. As Samaras had feared, the five-second window was too narrow. Over the next hour the Kiva fired five more rockets and triggered three strikes. But the Kahuna could not be readied in time.

Samaras left the mountain with some beautiful imagery from the Phantoms but once again without the long-awaited shot.

With another season over, Samaras retreated to a home he had recently purchased on a hill east of Denver overlooking the Colorado plains. But he is far from giving up the chase. He has installed an array of 12 computers to drastically reduce the Kahuna’s download time. And with help from a government contract, he is building a “snorkel van” to house the camera, which will be attached to a periscope on the roof that can be nimbly turned in all directions. I would be surprised if he isn’t out there now, one eye on the road and the other on a new storm throwing violent colors onto his laptop screen.

“I’m still in hot pursuit of that image,” he told me. “And I won’t stop until this is done.”

George Johnson’s most recent book is The Ten Most Beautiful Experiments. Carsten Peter’s story on Mount Erebus in Antarctica appeared last month.

Society Grant Tim Samaras’s lightning and tornado research is funded in part by your Society membership.
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