4. The Role of Thunderstorms in Red Lightning Formation
Red lightning is formed in great part from thunderstorms. These atmospheric disturbances produce the required environment for sprites and other higher atmospheric electrical events to occur. Usually, red lightning is connected with very strong thunderstorms, particularly those that generate positive cloud-to- ground lightning strikes. Less often occurring than negative strikes, these positive strikes move a lot of electrical charge from the cloud to the ground. An powerful electromagnetic pulse produced by this abrupt charge spreads upward into the mesosphere. Red sprites and other associated events are produced when this pulse interacts with the rarefied gases in the top atmosphere. The probability and frequency of red lightning events are strongly influenced by the magnitude and intensity of the thunderstorm as well as by its electrical properties. Fascinatingly, not all thunderstorms generate red lightning; the phenomena is more usually seen over big, long-lived storm systems called Mesoscale Convective Systems (MCS). These systems give several chances for the formation of upper atmospheric discharges since they can span hundreds of kilometres and last several hours. The intricate interaction between the lower and higher atmosphere during thunderstorms emphasises the linked character of Earth’s electrical system and the need of research of these events to better grasp the atmospheric dynamics of our planet.