thunderbolts

Thunderbolts are the visible electrical discharges produced during thunderstorms, commonly called bolts of lightning. The term can refer to a single stroke or a sequence along a channel, often accompanied by a sharp thunderclap. Lightning results from rapid electrical breakdown of air in a thunderstorm.

In a thunderstorm, charge separation within a cumulonimbus cloud builds up positive charge near the top and negative charge lower down. When the electric field becomes strong enough, air ionizes and a conductive channel forms, typically via a stepped leader from cloud toward the ground. A return stroke then travels along the channel, producing the bright flash. Lightning channels can reach temperatures around 30,000 kelvin and currents of several thousand to tens of thousands of amperes, with the rapid heating creating the characteristic thunder.

Common forms include cloud-to-ground, intra-cloud, and cloud-to-cloud discharges. Ground-to-cloud flashes and upward strokes from tall objects are less common. Some storms also produce upper-atmosphere discharges such as sprites and jets that are linked to the same electrical activity above the cloud.

Thunderbolts can pose risks of fire, injury, and property damage. Safety guidance emphasizes seeking shelter indoors, avoiding open areas, and staying away from tall objects, water, and metal conducts during storms.

Historically, thunderbolts have featured in cultures as symbols of power and divine authority, while scientifically they have been central to studies of atmospheric electricity and lightning protection since the 18th century.