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Lightning and discharge
Beginner
Charge separation in clouds produces huge potentials.
Cloud charge separation creates potentials of 10⁸ V; air breakdown forms a leader channel and a return stroke carrying 30 kA. Lightning rods provide a safe path.
Typical strike delivers 1–5 GJ.
Thunder is the shock wave of heated air.
In more detail
Lightning is a huge electrical discharge through air, when the field becomes high enough to ionise air molecules. The discharge equalises potential between clouds and ground.
Real-world uses
- Lightning rods protect buildings by providing a safe path to ground.
- Atmospheric scientists use lightning detection to track storms.
- Lightning forms when charge separates in storm clouds and builds a potential difference large enough to break down the air.
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Frequently asked questions
Why does lightning strike tall objects?
Tall objects reduce the distance to the cloud, concentrating the field there.
Is it safe to shelter in a car?
Yes, the metal body protects occupants by conducting the current around them.
Why do we see lightning before we hear thunder?
Light travels much faster than sound, so the flash arrives first, and the thunder follows as the sound reaches us.
Related topics in Electrostatics
Spherical capacitor · Cylindrical capacitor · Van de Graaff generator · Photocopiers and electrostatic precipitators · Millikan oil drop experiment · Motion of charge in uniform field