Question

What is lightening? Explain in terms of electric breakdown.

Answer 1

Lightning is a large-scale natural spark discharge that occurs within the atmosphere or between the atmosphere and the Earth’s surface.

Electrical breakdown occurs within a gas when the dielectric strength of the gas is exceeded.
Although air is normally an excellent insulator, when stressed by a sufficiently high voltage, air can begin to break down, becoming partially conductive. Across relatively small gaps, breakdown voltage in air is a function of gap length times pressure. If the voltage is sufficiently high, complete electrical breakdown of the air will culminate in an electrical spark or an electric arc that bridges the entire gap.
The color of the spark depends upon the gases that make up the gaseous media. While the small sparks generated by static electricity may barely be audible, larger sparks are often accompanied by a loud snap or bang. Lightning is an example of an immense spark that can be many miles long.