Differences in Positive and Negative Lightning Leader Appearance and Behavior as Observed by High-Speed Cameras

Since 2007, high-speed camera observations of lightning have been made in the Black Hills area of South Dakota. Numerous recordings of naturally occurring negative and positive cloud-to-ground flashes, intracloud flashes with visible leaders, upward lightning from towers and horizontally extensive “spider lightning” were captured at up to 100,000 images per second. Analysis of these observations along with correlated National Lightning Detection Network and electromagnetic sensor data shows clear differences in the appearance and propagation behavior between positive and negative polarity leaders. We present these differences and discuss how insight gained from high-speed recordings allows for increased analysis potential and, in many cases, leader polarity determination of standard-speed video and digital still optical recordings as well as real-time visual observations.