Consider the Earth and a cloud layer of 900 m above the planet to be the plates of a parallel-plate capacitor.
(i) When the cloud layer consists of an area of 1.0 km2 = 1000000 m2, determine the capacitance?
(ii) When electric field strength greater than 3.0 x 106 N/C causes the air to break down and conduct charge (lightning), determine the maximum charge the cloud can hold?