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The discharging current in the atmospher...

The discharging current in the atmosphere due to the small conductivity of air is known to be 1800 A on an average over the globe. Why then does the atmosphere not discharge itself completely in due course and become electrically neutral ? In other words, what keeps the atmosphere charged?

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The occurrence of thunderstorms and lighting charges the atmosphere continuously. Hence, even with the presence of discharging current of 1800 A. the atmosphere is not discharged completely. The two opposing currents are in equilibrium and the atmosphere remains neutral.
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The earth's surface has a negative surface charge density of 10^(-9)C m ^(-2). The potential difference of 400 kV between the top of the atmosphere and the surface results (due to the low conductivity of the lower atmosphere) in a current of only 1800 A over the entire globe. If there were no mechanism of sustaining atmospheric electric field, how much time (roughly) would be required to neutralise the earth's surface? (This never happens in practice because there is a mechanism to replenish electric charges. namely tghe coontainual thunderstorms and lighting in different parts of the globe). (Radius of earth =6.37 xx 10 ^(6) m.)

What are the forms, of energy into which the electrical energy of the atmosphere is dissipated during a lightning ? (Hint : The earth has an electric field of about 100 Vm^(-1) at its surface In the downward direction, corresponding to a surface charge density = - 10^(-9) cm^(-2) . Due to the slight conductivity of the atmosphere up to about 50 km (beyond which it is good conductor), about + 1800 C is pumped every second into the earth as a whole. The earth, however, does not get discharged since thunderstorms and lightning occurring continually all over the globe pump an equal amount of negative charge on the earth).

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