Lightning strikes are preceded by “glows” of gamma ray radiation, scientists find. (Credit: Breno Machado/Unsplash)

Summer in the U.S. brings big thunderstorms. Towering thunderhead clouds fill the skies and energy permeates the air as positive and negative electrical charges build up between the earth and the atmosphere. Lightning bolts reset the tension with a tremendous jolt of energy.

Now researchers discover glows of gamma rays – high-energy electromagnetic radiation – appear just b