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 Lightning is a discharge of atmospheric electricity that is triggered by a buildup of differing charges within a cloud. The result is a sudden release of energy that causes a distinctive bright flare, followed by a thunderclap.

There are several competing theories to explain why differing electrical charges appear in clouds, although scientists suspect that it may be related to the presence of ice crystals. Typically, the bottom of a cloud becomes negatively charged, and it sends out what is known as a “leader” that seeks a positive charge, either in another cloud or on the earth. As the leader approaches an area that is positively charged, a positively charged streamer emerges, meeting the leader, sealing the connection, and generating a bolt of lightning.