Posts Tagged high-speed observations
“Optical Observations of Needles in Upward Lightning Flashes” published in Nature Scientific Reports
Our latest peer-reviewed journal paper “Optical Observations of Needles in Upward Lightning Flashes” was published on 15 Oct 2020. It is open access and available for download at the link below.
The paper describes how attempted branches on positive leader channels can pulse well after the leader tip continues propagating away. These pulsing features are defined as “needles” and in rare cases, they can develop into a negative leader branch.
The online version of the paper which includes supplementary video can be found at this link.
Saba, M.M.F., A. R. de Paiva, L. C. Concollato, T. A. Warner and C. Schumann (2020), Optical observation of needles in upward lightning flashes. Sci Rep 10, 17460 (2020) doi:10.1038/s41598-020-74597-6
This is one of the best positive cloud-to-ground flashes that I have filmed. When you watch the video remember that lightning leaders grow as bidirectionally with a positive and negative end. We see the positive leaders of this flash below cloud base and the negative end of the leader network is higher up in the clouds and therefore not visible. There are two sets of positive leaders to focus on. The farther leaders are on the left descending to ground and the right positive leaders closer to the camera spread out horizontally along cloud base. Once the far positive leaders reach ground a return stroke occurs. Once the return stroke traverses the leader network, the connected channel grows as an upward propagating negative leader higher up in the storm. The closer leaders also have a negative end that is growing unseen in the upper part of the storm but these leaders do not connect with ground and continue to spread out horizontally. Frequently, some of the positive leader branches become cutoff and develop fast moving bidirectional recoil leaders that attempt to reionize the decayed positive leader branches. The negative end of the recoil leaders travel toward the negative end of the flash by racing toward the place where the positive leaders emerged below cloud base. This continues for quite some time. You may consider this to be a hybrid flash with a ground flash component (farther) and an intracloud flash component (nearer) both raising negative charge upward toward a positive charge region. This flash was filmed at 5,600 images per second.