Consider the earth and a cloud layer 900 m above the planet

Question

Compute all parts of given problem:

Problem: Consider the Earth and a cloud layer 900 m above the planet to be the plates of a parallel-plate capacitor.

Part A: If the cloud layer has an area of 2.0 km2 = 2000000 m², what is the capacitance?

F

Part B: If an electric field strength greater than 3.0 x 10⁶ N/C causes the air to break down and conduct charge (lightning), what is the maximum charge the cloud can hold?

C

I need expert help to solve the above problem.