Atmospheric Conditions Associated with Lightning during Snow and Ice Events

The purpose of this research was to find the atmospheric mechanisms associated with lightning in snow and ice events. The specific mechanisms that were examined were low-level wind shear, upper level divergence, surface temperature, low-level temperature, the -10 ° C level, and precipitable water. A chi-squared dependency test showed the strong association of low-level wind shear to each precipitation type (snow, sleet/freezing rain, rain) in two separate studies. Surface temperature appeared to have a relationship to lightning in all precipitation categories, while no significant relationship to lightning in all precipitation categories, while no significant relationship was found with upper level divergence, the -10 ° C level, or the precipitable water. From examination of the vertical soundings, temperatures above freezing are found in the low levels for all precipitation types meaning that different types of hydrometeors are present in the clouds. The mixing of these due to the turbulent effects of low-level shear may explain how the thunderclouds (mostly stratiform) are charged. Graupel and snow pellet interaction are also believed to be mechanisms for cloud charging