Overview

• Published July 28, 2025 in the Journal of Geophysical Research, the paper is led by Victor Pasko and collaborators from Penn State, NASA Goddard and European research institutes.
• Researchers demonstrate that strong thundercloud electric fields accelerate cosmic-ray electrons in collisions that emit X-rays and initiate cascading electron avalanches.
• The photoelectric feedback discharge model captures the chain reaction that generates terrestrial gamma-ray flashes and culminates in lightning strikes.
• Simulation results were validated against field data from ground-based sensors, satellites and NASA’s high-altitude spy planes.
• The framework accounts for gamma-ray flashes occurring without visible light or radio bursts by showing how electron avalanches can proceed optically dimly and radio silently.