Definition of Thunder
Thunder is the auditory manifestation of air swiftly expanding in response to the severe heating induced by a lightning discharge. As a lightning bolt journeys through the sky, it escalates the temperature of the adjacent air to extreme levels. This thermal surge prompts the air to expand instantly, engendering a shock wave that traverses the atmosphere, culminating in the booming resonance recognized as thunder.
Relation Between Lightning and Thunder
The phenomena of lightning and thunder maintain a fundamental connection, with thunder ensuing directly from a lightning discharge. A thunderstorm engenders lightning when an electric discharge evolves within it, neutralizing the electric potential disparity between the terrestrial surface and the tempestuous cloud. The energy liberated by this discharge heats the circumambient air, provoking the genesis of thunder.
Types of Thunder
Various types of thunder exist, distinguished by sound attributes and the proximity of the lightning strike. Claps refer to abrupt, resonant sounds that typically signal a close lightning strike. Peals denote sounds that fluctuate in pitch and volume, often resulting from multiple lightning discharges or sound reflections off nearby structures. Rolls represent prolonged, grumbling sounds originating from distant lightning strikes or from thunder resonating through disparate atmospheric layers.
Thunder and the Speed of Sound
The speed of sound in the atmosphere significantly influences our perception of thunder. Sound propagates at approximately 1,125 feet (or 343 meters) per second in dry air at 68°F (20°C). Given this finite speed, a delay transpires between the observable lightning flash and the audible thunder, with sound reaching an observer after the light. To crudely gauge the distance to a lightning strike, one can count the seconds between the lightning flash and the thunder, dividing this count by five for the distance in miles, or by three for kilometers.
Thunderstorms and Safety Precautions
Thunderstorms can generate intense weather conditions, including potent winds, hail, heavy precipitation, and lightning. Consequently, it is paramount to undertake safety measures when thunder is discernible. The 30-30 rule is a practical guideline for ascertaining safety during a thunderstorm. After witnessing a lightning flash, one should time the seconds until the thunder is perceptible. If this interval is less than 30 seconds, one should seek shelter immediately, and remain indoors for at least 30 minutes following the last audible thunder to ensure the storm has dissipated.
Thunder in Folklore and Culture
Historically, thunder has elicited both fascination and trepidation, often ascribed to the deeds of deities or supernatural entities. Numerous cultures harbor myths and legends about thunder, typically entailing divine beings who employ thunder and lightning as instruments to express their power. In contemporary times, thunder continues to command reverence and awe, serving as a testament to the formidable power of nature.