Indian Scientists Measure 1.3-Billion-Volt Thunderstorm, The Strongest On Record
Specifically, the Gamma Ray Astronomy at PeV EnergieS Phase-3 (GRAPES-3) muon telescope measures high-energy particles from outer space called cosmic rays. The GRAPES-3 researchers added electric field monitors to the experiment, and devised a way to turn these muon fluctuations into measurements of the voltage of passing storms. Michael Cherry, physics professor at Louisiana State University in Baton Rouge, told the science publication Physics that it was a unique but indirect way to measure the electric fields in thunderstorms, and the assumptions used in the analysis might not apply to every storm.
Source: gizmodo.com