Consider the Earth and a cloud layer 700 m above the planet to be the plates of a parallel-plate capacitor. (a) If the cloud layer has an area of 5.0 km2 = 5000000 m2, what is the capacitance? (b) If an electric field strength greater than 3.0 x 10 N/C causes the air to break down and conduct charge (lightning), what is the maximum charge the cloud can hold