Wouldn't Charge Flow On Power Lines Due to Capacitance
Any situation where you have something with charge, some dielectric spacing, and something else with charge will have capacitance. So pretty much everything.

In your case, the capacitance is just very, very small. Small capacitance gives a large impedance to both AC and DC. 

When you have direct contact with the earth, body capacitance to earth is usually spec'd at 100pF (already very small). If you were floating in mid-air as you say, this adds more spacing further decreasing this capacitance (with respect to earth), as you would find from this formula the effect of increasing \$ d \$.



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