What part of a thunderstorm kills the most people each year?

Lightning

Explanation:

Lightning strikes are electrical discharges that occur when clouds charge electrically. In a storm, lightning is the factor that kills more people each year. They can be seen through irregular and branched trajectories approximately 2 to 5 cm. For such a discharge to occur it is necessary that the soil has an electrical charge opposite to that contained in the clouds, because this way the attraction between them occurs and finally the discharge is released by the cloud.

Lightning can occur between clouds when they begin within one of these clouds (presenting no direct risk to the ground but to aircraft) and between clouds and soil that can begin both in the cloud and on the ground (with those beginning in the clouds presenting greater soil hazard).