The waves from a radio station can reach a home by two different paths. One is a straight-line path from the transmitter to the home, a distance of 30.0 km. The second path is by reflection from a storm cloud at an unknown height that is midway between the transmitter and the home. If the wavelength of the radio broadcast by the radio station is 400 m and there is a phase change upon reflection from the cloud, find the minimum height of the storm cloud that will produce destructive interference between the direct and reflected beams. The answer is 2.46*10^3 km. Please show the work and any formulas used.