Historical research guide · 0650 · 2023
Modeling the Neuruppin ball lightning incident
Karl D. Stephan
In one minute
On a January afternoon in 1994 a very large positive lightning stroke — 370 kiloamperes, logged by the German lightning-location network — hit the ground a few kilometres from the town of Neuruppin in Brandenburg. In the minutes that followed, people all over the town saw glowing balls: at least ten separate objects, reported by numerous witnesses, indoors and out. Karl Stephan, an electrical engineer at Texas State University, asks the question a physicist should ask about a case like that — not whether the witnesses were right, but what electrical conditions could produce ten of these at once. His answer is failed leaders. When lightning strips a huge charge out of a cloud, the electric field at ground level can be driven to roughly a million volts per metre over a wide area, and grounded objects everywhere start throwing upward leaders. Most never reach the cloud, but they still carry real current — a plasma channel at many places at once. Stephan ends by proposing laboratory experiments to test it.
Connection
Chapter 9 needs cases where a plasmoid can be tied to a measured electrical event, and Neuruppin is the best of them: many independent witnesses, a wide-area outbreak and an instrument-recorded 370-kiloampere stroke to anchor it. Chapter 1’s evidence ladder gets a clean rung here too, because Stephan turns a set of eyewitness reports into a circuit problem with numbers in it. Read it beside Alexander Keul’s case history at /library/stm-48b6e644d4, which logs the same event, and beside the electrodynamic model at /library/stm-90f3c174b1.
From the source
In 1994 a 370-kiloampere positive cloud-to-ground discharge about 5 km east of Neuruppin, Germany was immediately followed by the production of at least ten ball lightning objects, seen by numerous eyewitnesses.Abstract, opening sentence
Conditions at Neuruppin favoured the propagation of failed leaders — lightning leaders emerging from the ground that never connected to a cloud-based leader, but that could still have carried significant currents at multiple locations at once, which is what an outbreak of many simultaneous objects requires.Abstract; the failed-leader model
The proposed sequence of events explains how a ground-level electric field of about one million volts per metre could be produced by negative leaders extending into a region of positive charge above the town, with a large quantity of charge then transferred horizontally between the cloud-to-ground discharge and the region of high field.Abstract; the proposed sequence
The sequence is built on the published behaviour of ordinary lightning rather than on any new physics: upward lightning triggered by cloud-to-ground flashes, positive cloud-to-ground flashes in severe storms, the fundamental limit on electric fields sustainable in air, and the transfer of corona space charge between ground and thundercloud.Reference list (Schumann, Saba and Warner 2019; Rust, MacGorman and Arnold 1981; Dwyer 2003; the 1987 IVY-MIKE explosion-induced lightning study)
Laboratory plasmoids are treated as the relevant analogues — long-lived plasmoids produced in humid air, and ball-lightning-like plasmoids ejected from silicon by localized microwaves — which is what makes the model testable on a bench rather than only in a storm.Reference list (Egorov and Stepanov 2002; Meir, Jerby and Barkay 2013)
The paper closes with recommendations for laboratory experiments: the way to settle a failed-leader origin is to reproduce the field strengths and the charge transfer in the laboratory and see whether the objects appear.Abstract, closing recommendation
The way in
https://doi.org/10.1016/j.jastp.2023.106038How to cite it
Karl D. Stephan (2023) Modeling the Neuruppin ball lightning incident doi:10.1016/j.jastp.2023.106038