L.P. Babich All-Russian Scientific Research Institute of Experimental Physics — Federal Nuclear Centre, prosp. Mira 37, Sarov, Nizhny Novgorod region, 607190, Russian Federation
To assess the current state of explorations of nuclear reactions in thunderous atmosphere, observational data are reviewed of the neutron flux enhancements in thunderclouds and during thunderstorms related to photonuclear reactions on account of the bremsstruhlung of the avalanches of high-energy runaway electrons capable of evolving in the thunderous electric fields. Selecting thunderous neutrons is a challenging problem, since detectors are immersed in a mixed field of various penetrating emissions that includes, apart from neutrons, also the primary high-energy electrons and their bremsstruhlung. A special attention is given to a discovery of the electron-positron annihilation line with the photon energy 0.511 MeV in a thundercloud and on the Earth surface during thunderstorms, providing trustworthy evidence of the neutron production by thunderous atmosphere and photonuclear origin of thunderous neutrons. Consequences of this discovery are discussed.