The voltage of a cloud is 4 × 10⁶ volts with respect to ground. In a lightening strike lasting 100 ms^-1, a charge of 4 coulombs is delivered to the ground. The power of the lightening strike is:

160 MW

Work done = charge × potential difference

W = 4 × (4 × 10⁶ - 0) = 16 × 10⁶ J

Power of the lightening strike,

P = $\frac{W}{t} = \frac{16 \times 10^6}{100 \times 10^{-3}}$ = 160MW