Observation of Vertical and Tortuous Lightning Channels Using a High-Speed Camera

Lightning data acquisition methods in Malaysia have begun to incorporate advanced tools such as high-speed cameras. However, comprehensive reports on the results of this method are still limited. Due to this circumstance, little is known about the characteristics of optical lightning. Thus, this study was carried out using a high-speed camera installed in Malacca, Malaysia. An investigation was conducted into the optical profile of the cloud to ground lightning channel termination. Temporal analysis has been conducted on the termination behaviour of 37 discharge channels, including vertical and tortuous return strokes, solely based on the camera records. It was discovered that 68% of the return strokes were tortuous and 32% were vertical lightning channels. Multiple strokes lightning for both vertical and tortuous events were observed in 25% and 24% of the sample, respectively. From 22 first return stroke samples, 57% of vertical and 53% of tortuous channels ended at a new location than the previous first return stroke. All 24 subsequent return strokes in total for both vertical and tortuous lightning used the same channel with the preceding first return strokes and terminated at the same location. Both vertical and tortuous channels produced first return strokes at 143 ms and 129 ms of interval, while subsequent return strokes were produced at 47 ms and 29 ms of interval respectively. All these findings contribute to the field of lightning physics, particularly in relation to optical lightning observation in Malaysia. Despite its scarce occurrences, the flashes with multiple striking points on the ground within a short duration might produce fatal damage. Thus, they should be taken into consideration in designing lightning protection.