To create an image of thunder, Dayeh and his colleagues devised “a special ear to hear where thunder is coming from.” Their technique relies on a rocket carrying a conductive copper wire, which provides a predictable path for lightning to follow. An array of 15 microphones sitting on the ground then collected the sounds associated with the triggered strikes.
“Instead of waiting for a lightning strike, you bring lightning to you,” Dayeh says. The team conducted their experiments last July 14, when conditions were ripe for thunderstorms near Gainesville, Florida. After the rocket went up, a flash of green lit the sky. This was the copper wire burning up. Then nine purplish flashes zigzagged to the ground, accompanied by thunder that was recorded with the microphones. Dayeh took those recordings and processed them to create an image of the sound.