Scientists measure electric fields in thunderclouds with instruments aboard airplanes and weather balloons, but during violent conditions these methods can be difficult, even dangerous.

Now researchers may have found a better way to measure these electrical fields: the cosmic rays that originate from exploding stars.

When cosmic rays hit the Earth’s atmosphere, they create a shower of high-energy particles. Researchers in the Netherlands measured the radio emissions generated by these showers and found that they varied markedly during fair weather and thunderstorms. The differences may provide an effective way to estimate the electric field in a thunderhead.

Monitoring a cloud’s electric field is important because it helps define the power of a thunderstorm, said Heino Falcke, an astrophysicist at Radboud University and one of the study’s authors.