1. The problem statement, all variables and given/known data (a) It is estimated that the average electric charge carried in a lightning flash is 5C. If the p.d. between the cloud and the ground is about 800 MV, approximately how much energy is transferred in a flash? (b) In a typical thunderstorm, lightning flashes strike the ground at intervals of about 3 minutes. Over the whole surface of the Earth the total current carried in this way between the atmosphere and the ground averages 1800 A. Estimate the average number of thunderstorms taking place at any instant over the whole Earth. 2. Relevant equations W=VQ Q=It Anything else? 3. The attempt at a solution For part (a), it was quite simple: 5 * 800 * 106 = 4 * 109 Joules. But for part (b), I am stumped; don't know where to begin. Could you please help? Thank you!