# What is the optimum altitude for tapping atmospheric charge?

The atmosphere appears to have a large potential difference (voltage) in relation to ground. The obvious example is the thunder where this voltage becomes large enough to break the insulator - air. Of course the fact that thunders are not permanent indicates a gradual build up of charge that is released to equalize (in the lack of a better word) the potential difference as a result.

I suppose that different layers of the atmosphere have different electrical characteristics and I wonder if there is a layer that has a rather stable potential difference rather than depending on the charge carried by storms.

I watched the following video and I noticed that (if his numbers are correct) even though the voltage was quite high, the current produced was minuscule.

https://youtu.be/2rVdEhyMR6A

I believe his choice of 120 meters or 390 feet was due to the maximum (legal) altitude restriction for drones and not because that is where they really got the optimum results - i.e. if they were allowed to fly higher, they would get more current. But what is the physical optimum altitude for tapping atmospheric charge?

The background story is that as a child I used to like science fiction and at some point I was imagining what if we could pull a wire to space so that the centrifugal force acting on it was equal to the forge of gravity and it would stay put. Could we then put our electrical devices in series and power them?

Of course growing up made me realize that this might not be as simple as I once thought but I still wander back to that thought experiment from time to time.

Please keep any discussion about my thought experiment in the comments to stop this from becoming a discussion rather than an answerable question.

• have you seen this ? feynmanlectures.caltech.edu/II_09.html – anna v Feb 3 '18 at 13:58
• Try looking up articles on STS-75 and the tether they used. One problem is that any lengthy tether system would require attitude adjustments from one or both orbiting objects, since the lower altitude object will orbit faster. To put one end on the ground would require materials and other things we do not have (e.g., money, patience, initiative, motivation) but in principle, a highly conductive wire could supply some power. The amount depends upon the length and conductivity of the wire and the plasma conditions. – honeste_vivere Jan 30 at 19:31