Cloud-to-ground lightning occurs when the electrical charge travels between a negatively charged cloud base and the positively charged ground. This is the most spectacular variation of lightning, forming brilliant, jagged bolts between the sky and the ground. Each lightning stroke lasts a fraction of a second. Sometimes a number of strokes is needed to discharge the electrical build-up, giving the lightning a flickering appearance. Often the main stroke combines with smaller offshoots that discharge into the air or inside the cloud.
