Not really, the energy density is fairly low. Except during thunderstorms of course. Shoudn't be too hard to check. Get ten metres of rigid plastic pipe and

Not really, the energy density is fairly low. Except during thunderstorms of course. Shoudn't be too hard to check. Get ten metres of rigid plastic pipe and ten metres of insulated wire bared at the ends so that you can measure the voltage between the top and ground. Set it up vertically at least 20 m from everything else. Measure the voltage between top and bottom with a good quality high impedance voltmeter. Now add another ten metre length of wire and a resistor to complete the circuit and use some of the power. Measure the voltage again. The voltages and the resistance allow you to calculate the equivalent impedance of the source. I'd be very surprised if no one has already done this and probably in a much more sophisticated fashion.