The Role of Lightning in Generating Gamma Rays Revealed
A groundbreaking moment in science has been captured, shedding light on the process by which lightning on Earth generates powerful gamma rays. For the first time, researchers have observed the formation of a lightning bolt and its connection to terrestrial gamma-ray flashes (TGFs).
Conducted in Kanazawa City, Japan, a team led by physicist Yuuki Wada from the University of Osaka utilized advanced sensors to capture the collision of electrical currents that lead to the creation of gamma rays. This observation confirms the theory that TGFs associated with lightning are a result of powerful electrical fields accelerating electrons to nearly the speed of light.
According to Wada, “Studying extreme processes like TGFs originating from lightning helps us understand the high-energy phenomena occurring in Earth’s atmosphere.”
While the formation of cloud-to-ground lightning is rapid, it requires a conductive path to be established by a lightning leader. These leaders can emerge either downwards from clouds or upwards from the ground, providing the necessary channel for electric currents to flow.
The phenomenon of TGFs is believed to arise from the acceleration of electrons to near-light speeds in strong electric fields created by thunderstorms. These cascades, known as relativistic runaway electron avalanches, are responsible for the production of TGFs.
When these accelerated electrons suddenly decelerate due to collisions with atmospheric nuclei, the energy loss results in gamma rays, a form of deceleration radiation called bremsstrahlung radiation.
The research team deployed a comprehensive sensor setup capable of monitoring lightning across various wavelengths, revealing that TGFs precede lightning bolts, albeit by minuscule time increments that are imperceptible to the naked eye.
Prior to the convergence of oppositely charged lightning leaders, a concentrated electric field emerged, accelerating electrons to relativistic speeds. The detection of the first gamma-ray photon occurred just microseconds before the leaders collided, with the full TGF burst extending beyond the lightning strike formation.
This groundbreaking observation provides detailed insight into how lightning storms can generate gamma radiation, the most energetic form of light in the electromagnetic spectrum. Physicist Harufumi Tsuchiya of the Japan Atomic Energy Agency highlights the significance of these multi-sensor observations in advancing our understanding of these radiation bursts.
The research findings have been published in Science Advances, marking a significant milestone in unraveling the mysteries of TGFs associated with lightning.
