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Modeling hard radiation from streamers and leaders and terrestrial gamma-ray flashes

Terrestrial gamma-ray flashes are observed above thunderclouds. Energetic radiation is also reported from lightning leaders approaching ground, and it is measured during the initial streamerleader phase of meter-long spark discharges in the laboratory. We study the generation of such radiation by streamer coronas and leaders and present three results: First, with our numerical hybrid code, we have developed a numerical tool with limited numerical costs that accurately follows the acceleration and run-away of individual electrons from a negative streamer. Second, we present effective differential cross-sections for Bremsstrahlung in air to determine the hard radiation, as well as cross-sections for the production of electron-positron pairs (antimatter). Third, we estimate the X-ray and gamma-ray emission above an upwards propagating negative intracloud leader.