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For other uses, see Thunder (disambiguation).
Thunder is the sound made by lightning.Depending on the nature of the lightning and distance of the listener, thunder can range from a sharp, loud crack to a long, low rumble (brontide). The sudden increase in pressure and temperature fromlightning produces rapid expansion of the air surrounding and within a bolt of lightning. In turn, this expansion of air creates a sonic shock wave which produces the sound of thunder, often referred toas a clap, crack, or peal of thunder. The distance of the lightning can be calculated by the listener based on the time interval from when the lightning is seen to when the sound is heard.erpo Thecause of thunder has been the subject of centuries of speculation and scientific inquiry. The first recorded theory is attributed to the Greek philosopher Aristotle in the third century BC, and an earlyspeculation was that it was caused by the collision of clouds. Subsequently, numerous other theories have been proposed. By the mid-19th century, the accepted theory was that lightning produced avacuum. In the 20th century a consensus evolved that thunder must begin with a shock wave in the air due to the sudden thermal expansion of the plasma in the lightning channel.[1] The temperature insidethe lightning channel, measured by spectral analysis, varies during its 50 μs existence, rising sharply from an initial temperature of about 20,000 K to about 30,000 K, then dropping away gradually toabout 10,000 K. The average is about 20,400 K (20,100 °C; 36,300 °F).[2] This heating causes it to expand outward, plowing into the surrounding cooler air at a speed faster than sound would travel inthat cooler air. The outward-moving pulse that results is a shock wave,[3] similar in principle to the shock wave formed by an explosion, or at the front of a supersonic aircraft. More recently,...