Lightning Leaders Collide, Triggering Gamma Ray Burst Over Kanazawa

Researchers from The University of Osaka have made a breakthrough in understanding lightning by capturing the first detailed observation of a terrestrial gamma-ray flash, or TGF, linked directly to a lightning strike. The study used advanced multi-sensor technology to track light, radio waves, and gamma rays during a storm in Kanazawa City, Japan. This discovery sheds new light on the high-energy physics involved in lightning.

Terrestrial gamma-ray flashes are very short but intense bursts of gamma rays that last only microseconds, making them difficult to detect. Scientists believe these flashes are caused by electrons accelerating to nearly the speed of light inside strong electric fields created by lightning.

During the storm, two lightning leaders were observed: one coming down from a thundercloud and another moving up from a transmission tower. These two lightning paths approached each other before colliding. A strong burst of gamma rays was recorded 31 microseconds before the leaders met, and radiation continued for 20 microseconds after they touched. The event produced a powerful lightning discharge with a current of -56 kiloamperes.

This observation confirms theories about how electrons reach relativistic speeds during lightning, supporting models that explain the creation of gamma rays through thermal runaway and feedback processes. The use of multiple sensors tracking different signals at the same time was a first in this field and has brought scientists closer to understanding these fast and intense radiation bursts.

Besides advancing scientific knowledge, these findings can help improve protection for infrastructure such as power lines and communication towers, which can be damaged by energetic lightning events. Better understanding of TGFs could lead to safer systems and reduce damage from storms.