Simulations and Theory of Lightning Initiation in Low Thundercloud Fields

This study seeks to theoretically investigate the lightning initiation in low thundercloud fields, that currently represents a fundamental unsolved problem in lightning discharge physics. The research promises to answer questions about the frequency of relevant hydrometeor (rain/snow/ice in cloud) collisions, the kind of discharge process or streamer activity that would be triggered, and the likelihood of conditions required for such discharge activity to escape and continue to develop on larger scales. A better understanding of electric fields around small particles could be of interest to industries like powder-coating and laser printing. The work includes training of young scientists and enables support of undergraduate research.

The investigators will, first, quantify the electric field between two spherical hydrometeors using the image charge method and between two non-spherical hydrometeors using the Poisson's equation, and apply the avalanche to streamer transition criteria to observe whether streamer initiation is possible. Second, the investigators will develop a fluid model consisting of continuity equations for positive and negative ions, and electrons coupled with Poisson's equation. Third, the investigators will apply streamer models to describe the streamer development between the two hydrometeors and the streamer escape to open space.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.