thunderclap

Thunderclap is the audible effect produced by a nearby lightning strike. It describes the sharp, explosive sound that observers hear when the rapidly heated air in the lightning channel expands and creates a shock wave in the atmosphere. A close lightning discharge is often heard as a single loud crack or clap, sometimes followed by a longer rumbling of distant thunder.

As the distance increases, the sound may be perceived more as a rolling thunder than a single crack. The perceived character depends on atmospheric conditions, terrain, and the speed of sound, which is about 343 meters per second in dry air at sea level.

Beyond its meteorological sense, thunderclap is used metaphorically to denote a sudden, drastic event that has an immediate and dramatic impact, such as a political or social upheaval. In this usage, the term thunderclap moment or thunderclap announcement is common in journalism and commentary.

Originating from the words thunder and clap, the term has long been used in English to describe storms and other explosive sounds.

Distance estimation: to gauge how far away a lightning discharge is, observers can count the seconds between seeing the flash and hearing the thunder; roughly 5 seconds per mile, depending on air conditions.