Why Do Thunderstorms Spew Out Gamma Rays?

On top of Kanazawa Izumigaoka High School, the wind whips at researchers Teruaki Enoto and Yuuki Wada as they wrestle with a boxy instrument, trying to secure it to the roof. A nearby weathervane swings ominously and clouds gather over distant mountains, all signs of the storm brewing in the direction of the Sea of Japan.