# phys: cloud-to-ground lightning often strikes twice (or more)

<< Lightning is a dangerous yet poorly understood natural phenomenon. Lightning forms a network of plasma channels propagating away from the initiation point with both positively and negatively charged ends-called positive and negative leaders. >>

<< Negative leaders propagate in discrete steps, (..) Positive leaders propagate more continuously and thus emit very little high-frequency radiation. >>

<< It has been inferred that positive leaders can become transiently disconnected from negative leaders, which may lead to current pulses that both reconnect positive leaders to negative leaders, and cause multiple cloud-to-ground lightning events. >>

<< The disconnection process is thought to be due to negative differential resistance ... >>

AA << find small plasma structures-which (they) call 'needles'- (..) that appear to drain charge from the leader, and are probably the reason why positive leaders disconnect from negative ones, and why cloud-to-ground lightning connects to the ground multiple. >>

B. M. Hare, O. Scholten, et al. Needle-like structures discovered on positively charged lightning branches. Nature. volume 568, pages360–363 (2019) Apr 17, 2019.

https://www.nature.com/articles/s41586-019-1086-6

Why lightning often strikes twice. New study reveals needle-like structures in positively charged lightning leaders. Univ. of Groningen Apr 17, 2019

https://www.eurekalert.org/pub_releases/2019-04/uog-wlo041619.php