A report is made on a comprehensive observation of a burst-like γ-ray emission from thunderclouds on the Sea of Japan, during strong thunderstorms on 2007 January 6. The detected emission, lasting for ∼40 seconds, preceded cloud-to-ground lightning discharges. The burst spectrum, extending to 10 MeV, can be interpreted as consisting of bremsstrahlung photons originating from relativistic electrons. This ground-based observation provides first clear evidence that strong electric fields in thunderclouds can continuously accelerate electrons beyond 10 MeV prior to lightning discharges.
@article{arxiv.0708.2947,
title = {Detection of high-energy gamma rays from winter thunderclouds},
author = {H. Tsuchiya and T. Enoto and S. Yamada and T. Yuasa and M. Kawaharada and T. Kitaguchi and M. Kokubun and H. Kato and M. Okano and S. Nakamura and K. Makishima},
journal= {arXiv preprint arXiv:0708.2947},
year = {2008}
}
Comments
12 pages, 4 figures, accepted for publication in Physical Review Letters