Electricity in the Atmosphere: Feynman's Physics Explained

Feynman Vol II9-10

On a clear day there is a downward electric field of about 100 volts per meter in the air — the Earth itself is negatively charged. This drives a small current that should drain the charge in about half an hour, so what keeps the Earth charged? Thunderstorms. They act like giant batteries, carrying negative charge down to the ground in lightning and positive charge up to the high atmosphere, maintaining a global electrical circuit.

The big idea

Thunderstorms are the batteries that keep Earth's global circuit charged.

Think about it

If the air constantly drains Earth's charge, why hasn't it run out over billions of years?

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