"Reg Edwards" wrote
About 20 years ago I measured the charge produced on a 150-feet,
long-wire, end-fed inverted-L antenna, using a DC, 0 to 50
micro-amp,
moving coil meter.

======================================

The VLF capacitance to ground of the 30-feet high antenna is about
250 pico-farads. Total capacitance including the air-spaced tuning
capacitor = 550 pico-farads.

Assuming a capacitor breakdown voltage of 2000 volts and a breakdown
rate of once per second, then leakage over several antenna insulators
must have been about 1800 megohms. A not unreasonable figure.

It's surprising what can be deduced from a simple but fundamental
relationship such as -

Q = C * V = I * T

where Q = capacitor charge in Coulombs, C = Farads, V = volts, I =
amps, T = seconds.

It's only arithmetic. ;o)

You could now estimate the receiver noise level in dBm, due to
precipitation of rain drops of given average diameter, on an antenna
at a rate of N drops per second, each drop charged up to a potential
of V volts relative to ground. You would, of course, have to take
receiver bandwidth and a lot of other things into account. So it's
probably not worth the time and trouble.
----
Reg.