PULSE Magazine | April 2019 Issue

Muons passing through the pyramid's stone walls lost more energy than muons passing through the large, empty chambers. The results allowed the researchers to create a new map of the pyramid's interior without setting foot inside of it. Gupta and his colleagues used a similar method to map the energy inside the Ooty thundercloud. Instead of contending with stone, however, muons falling through the cloud faced a turbulent electric field. "Thunderstorms have a positively charged layer on top and a negatively charged layer on bottom," Gupta said. "If a positively charged muon hits the cloud as it rains down from the upper atmosphere, it's going to be repelled and lose energy." [Infographic: How Lightning Works] Using an array of muon-detecting sensors and four electric field monitors spread over several miles, the researchers measured the average drop in energy between muons that passed through the thundercloud and those that didn't pass through it. From this energy loss, the team was able to calculate how much electric potential the particles had passed through in the thunder cloud.

It was massive.

"Scientists estimated that thunderclouds could have gigavolt potential in the 1920s," Gupta said, "But it was never proven — until now."

Mapping the thunder

Once the researchers knew the cloud's electric potential, they wanted to go a step further and measure precisely how much power the thundercloud carried as it roared over Ooty.

Using the data from their widely dispersed electric field monitors, the team filled in some important details about the cloud — that is was traveling at roughly 40 mph (60 km/h) at an altitude of 7 miles (11.4 kilometers) above sea level, had an estimated area of 146 square miles (380 square km, an area about six times the size of Manhattan), and reached its maximum electrical potential just six minutes after appearing. Armed with this knowledge, the researchers were finally able to calculate that the thunderstorm carried about 2 gigawatts of power, making this single cloud more powerful than the most powerful nuclear power plants in the world, Gupta said.

"The amount of energy stored here is enough to supply all the power needs of a city like New York City for 26 minutes," Gupta said. " If you could harness it."

With current technology, that's an unlikely prospect, Gupta noted: The amount of energy dissipated by such a storm is so high that it would probably melt any conductor.

Still, the violently powerful potential of thunderstorms could help settle a cosmic mystery that scientists like Gupta and his colleagues have asked for decades: Why do satellites sometimes detect high-energy gamma rays blasting out of Earth's atmosphere, when they should be raining down from space? According to Gupta, if thunderstorms can indeed create an electric potential greater than one gigavolt, they could also accelerate electrons quickly enough to break apart other atoms in the atmosphere, producing gamma-ray flashes.

This explanation requires more research to verify its accuracy, Gupta said. In the meantime, be sure to marvel at the next thundercloud you see, for it is an unfathomably mighty force of nature — and, please, think twice before flying a kite.

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