High‐speed X‐ray images of triggered lightning dart leaders

摘要: [1] We present the first high-time resolution two-dimensional images of X-ray emissions from lightning. The were recorded at a rate 10 million per second using new pinhole-type camera, located 44 m rocket-and-wire-triggered We report observations two dart leaders, one in each lightning flashes triggered during summer 2010 north-central Florida. In both events, as leader approached ground, source was also seen to descend along previous channel. For event, exhibited downward speed 4.5 × 107 m/s, agreement with independent dE/dt time-of-arrival (TOA) measurements front, demonstrating that front emission. camera bursts MeV gamma rays originating and/or ground attachment process leader. Overall, these results provide insight into production energetic radiation and propagation lightning, all which remain poorly understood.