Discord7 said:
If typical atmospheric lightning is developed from a negative charge accumulated upon rainwater, and negative charge is stated to be brought down by lightning, then wouldn't most rainwater tend to be of negative charge? It seems as though some negatively charged rain might reach the ground before it could become discharged by a stroke of lightning. Some positive rainwater might be encountered due to inductive kick upon lightning bolts, but that would necessarily be more than offset by the thunderbolt involved. Is there supporting evidence for the referenced author's contention that the Earth's atmosphere holds an opposing charge to that of the earth?
Dear Discord7, thanks for your questions and insights. I'm not the expert, so I can only refer to what Martin Uman had to say in 1986:
"The top of the lightning channel is found in the (lower) N-region of the cloud. The N-charge resides on supercooled water and ice particles. Stepped and dart leaders are negatively charged, drawing their charges from the N-region. The return stroke drains the negative charge of the leader to the ground. After the return stroke has reached the top of the lightning channel, the whole channel, a good conductor to the ground, becomes positively charged in response to the negative cloud charge above and around it. The leader-return stroke process results in a negatively-charged leader channel being replaced by a positively charged channel in a time that is short compared to that in which any of the surrounding negative cloud charge can move appreciably. If electrical effects cause the rain gush, the charged cloud particles must coalesce in response to the rapid change in the sign of the charge on the lightning channel. The mechanism for coalescence most closely examined is that proposed by Bernard Vonnegut and Charles Moore. They postulate that the cloud droplets in the immediate vicinity of the newly-completed return stroke channel acquire a net positive charge from the positively charged channel. Since similar charges repel one another, the positively charged droplets fly away from the channel, initially at perhaps tens of yards per second, colliding and coalescing with the surrounding negatively charged droplets. The initially stationary negative droplets are attracted toward the moving positive droplets by virtue of their opposite charge, further increasing the collision rate. The positive droplets may travel about 10 yards, increasing in size all the time. The end result is a group of large water drops surrounding the channel."
Moore, C.B., B. Vonnegut, et al, Radar Observations of Rain Gushes Following Overhead Lightning Strokes,
J. Geophys. Res., 67, 207-220 (1962)
Moore, C.B., B. Vonnegut, et al, Gushes of Rain and Hail After Lightning
J. Atmos. Sci., 21 646-665 (1964)
Moore, C.B., B. Vonnegut, et al, A Possible Effect of Lightning Discharge on Precipitation Formation Process,
Am Geophy. Union Monograph Number 5, 287-304 (1960)
As for Uman's ideas of how the electrical balance of the atmosphere is maintained, I think he got them from
Atmospheric Electricity, J.A. Chalmers, 2nd Edition, Pergamon Press, 1967.
Possibly Uman or others have progressed in their investigations since then. If so, it would be fun to learn about it.
Respectfully submitted,
Steve