A detection that shows how the atmosphere can very efficiently accelerate particles during lightning associated with powerful thunderstorms. The AGILE discovery challenges current models of TGF acceleration based on relativistic electron production and cascading, and leads to substantial revisions of extreme particle acceleration models in lightning. This investigations have very important impacts on the study of the atmospheric environment and implications for global climate change studies. AGILE obtained the first gamma-ray imaging of TGFs from space using a special technique of on-board data selection. The AGILE Team reported the surprising discovery of gamma-ray radiation up to 100 MeV in the paper by Tavani et al., PRL, 106, 018501, 2011.