Consider the Earth and a cloud layer 600 m above the planet to be the plates of a parallel-plate capacitor.
(a) If the cloud layer has an area of 3.0 km2 = 3000000 m2, what is the capacitance? F
(b) If an electric field strength greater than 3.0 multiplied by 106 N/C causes the air to break down and conduct charge (lightning), what is the maximum charge the cloud can hold? C