Lightning: formation, types, effects, detection

Definition and basic physical description of lightning

Lightning is a natural phenomenon caused by electrostatic discharges in the atmosphere between two electrically charged regions. One or both charge regions are typically within clouds, and the second region may sometimes be on the ground. After the discharge, the involved regions become partially or wholly electrically neutralized. A lightning flash releases energy very rapidly, with an average energy release on the order of hundreds of megajoules to several gigajoules. The air around the flash heats extremely quickly to temperatures of about 30,000 °C, producing bright light (visible as a flash) and emitting electromagnetic radiation across a wide range of wavelengths. The sudden heating also produces thunder, which is the sound from a shock wave created as the heated gases experience a rapid pressure increase. Lightning most commonly occurs during thunderstorms, though it can also occur in other energetic weather systems such as volcanic eruptions. The basic physical description is therefore an energetic, near-instantaneous electrical discharge through air, accompanied by intense heating, light, electromagnetic radiation, and (when conditions allow) thunder.

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Energy release and rapid heating in lightning

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