Lightning and thunder are complex atmospheric phenomena involving electrical processes. Thunderstorms typically form in cumulonimbus clouds, which develop when warm, moist air rises, forming tall vertical structures. Inside these clouds, updrafts and downdrafts cause collisions between water droplets and ice crystals, leading to triboelectrification—a process that separates charges.
The upper part of the cloud (above 10 km altitude) becomes positively charged as smaller ice crystals are lifted, while the lower part (below 5 km) becomes negatively charged due to heavier water droplets. This charge separation creates a strong electric field between the cloud and the ground, most intense near the cloud’s base.
As the electric field strengthens, a leader stroke, a narrow channel of ionized air, forms from the cloud toward the ground. The leader stroke, about 1-2 cm in diameter, is negatively charged and follows the path of least resistance. Once the leader stroke connects with the ground, a return stroke of positive charge surges back through the channel. This is the bright flash we see as lightning, which can reach temperatures of up to 30,000°C, hotter than the sun’s surface.
The return stroke’s immense speed, about 270,000 km/h, heats the surrounding air, creating a shockwave. This rapid air expansion causes the sound of thunder. Since sound travels slower than light, the thunder is heard after the lightning flash. By timing the interval between the two, we can estimate the lightning’s distance.
Several factors influence lightning formation, including humidity, which increases storm intensity, wind which can disperse charges, topography, as mountains force air upward, and weather fronts which create instability leading to storms. These conditions together drive the dramatic displays of lightning and thunder.
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