The event is well known: when the storm bursts, thunder rumbles. What is less is the way in which the electric charge of the cloud generates such noise. Here are some answers.
A cloud forms, electrifies itself and gives birth tothunderstorm. If theelectrification is intense, the cloud must discharge. The discharges appear in a luminous way, with flashes, and in a sound way: it is the thunder.
After the lightning, the shock wave of thunder
When a storm cloud, a cumulonimbusis formed, a electric field within the air mass. As the field increases, parts of the cloud ionize and generate lightning. These travel through the air along conductive channels. Some will never reach the ground (intracloud lightning), while others will hit it: they are then called lightning (or cloud-to-ground lightning). All lightning generates noise, but the word thunder most often refers to the shock wave caused by the return arc of the lightning.
After striking the ground, lightning forms a very intense current wave which travels through the conductive channel. The reverse current is so powerful that it heats the channel by Joule effect at temperatures of around 30,000°C. The brutal dilation generates a shock wavewhich we perceive ultimately in sound wave : Thunder.
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