fulmine

Fulmine, in meteorology, is the natural electrostatic discharge produced during thunderstorms, manifested as a bright flash and accompanied by thunder. The term derives from Latin fulmen, meaning thunderbolt.

Lightning forms when a strong electric potential builds between regions of opposite charge within a cloud, or between a cloud and the Earth's surface. Charge separation occurs mainly due to collisions between ice particles in tall cumulonimbus clouds. When the electric field becomes strong enough, a conductive path called a leader forms and a rapid discharge propagates as a return stroke, heating air to tens of thousands of kelvin and producing light.

Types of discharge include cloud-to-ground, cloud-to-cloud, and intracloud discharges. The most familiar is cloud-to-ground, where the current travels from the cloud base to the ground and is often followed by a thunderclap. Lightning can also transfer charge between clouds or within a single cloud, producing bright flashes without striking the surface.

Globally, about 1.4 billion flashes occur each year; lightning causes property damage, wildfires, and injuries or fatalities, though it also contributes to atmospheric chemistry and the breakdown of pollutants. Lightning is detected and studied by meteorological networks, ground-based sensors, satellites, and other instrumentation. Protection measures include proper bonding and grounding of structures, air terminals, and avoidance of exposed locations during storms.