GoKawiilBefore he changed the way we understand lightning on Earth, Joseph Dwyer studied the weather in more cosmic settings. Using the sensors on NASA’s Wind satellite, orbiting a million miles away, he watched flares shoot out from the sun and analyzed the particles that stream from the sun’s surface. But when he relocated to Florida around the turn of the millennium, Dwyer felt ready for something new — something he and his students could investigate on their own. It didn’t take long before the tropical weather delivered a suitable mystery outside his office window. “It was like boom, boom, boom outside,” Dwyer said. “I looked into it and realized lightning was an unsolved problem.”
Thunderstorms have captivated humanity for millennia, and yet their inner workings remain deeply mysterious. Storm clouds are opaque. They’re dangerous to approach. And they’re too big to fit in a lab. Inquisitive researchers have been sending kites, balloons, and rockets up into them for nearly three centuries, and they’ve learned a lot. But every time lightning lovers get closer to the action, they discover major gaps in their understanding. For the past 50 years, researchers have focused on one particular gap: How does the jagged channel of white-hot air we call a lightning bolt get started?
Joseph Dwyer pioneered lightning research by turning instruments designed to study violent cosmic events toward thunderstorms. Courtesy of Joseph Dwyer
Recently, the field has experienced a sort of renaissance as researchers — many of them astrophysics refugees like Dwyer — have devised new ways to pierce the clouds. They’ve taken a slew of instruments built to study violent cosmic events and trained them on the brutality of terrestrial thunderstorms. They’ve seen lightning shooting out X-rays as it zigs and zags, spotted flickering glows of gamma rays coming from thunderclouds, and, very recently, detected hints of bolts traveling in unexpected directions.
No one has put all the pieces together, but a new understanding of lightning is taking shape. The fearsome flashes look less and less like the supersize electric sparks that physicists once imagined them to be. While electricity plays a central role, lightning bolts are formed and shaped by the whole physics canon — from cosmic blasts to particle physics. In particular, triggering a bolt seems to require extreme events more typically associated with supernovas, black holes, and particle colliders than with fluffy clouds.
“There is a growing consensus in the field that high-energy processes play a critical role in lightning initiation,” said Caitano da Silva, an atmospheric physicist at New Mexico Tech. “It’s an exciting time to be in this field.”
Trigger Point
When lightning bolts split the sky, the ancient Greeks, Scandinavians, and Hindus saw flashes of divine warfare. And when thunderclaps rattled their chests, the Chinese felt a deity punishing wrongdoers. Today, the power of thunderstorms still leaves people awestruck.
“I grew up watching these large cold fronts coming in with a lot of lightning” in Brazil, da Silva said. “I grew terrified of it.”
With fear comes fascination. Yet despite centuries of exploration, fascinated physicists like da Silva are still asking the same question that the ancients did: How does lightning begin?
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