Well, I said it is “basic high-school physics” that a lightning rod dispels the charge from the ground because that’s what I was taught in high-school physics, in 1980. Maybe the teacher got it wrong. He did make a point of saying that a van der Graaf generator has a globe on top because that shape holds the charge on the surface and prevents it from dispersing, thus it builds up a charge that we see discharged in sparks when you put your finger close to it. A lightning rod, on the other hand, is pointy on top, which concentrates its electric (or was it magnetic?) field-lines at one point, which makes it possible for it to discharge electrons steadily and harmlessly, from the ground into the air, thus preventing the charge buildup which leads to a stroke of lightning.
Well that’s the ON (original nitpick) answered, now what was the OP again?
Yeah that’s how I understood it too. High school physics, no less.
This lightning-rod business is a scientific question and really belongs in GQ, so I started a thread there: “Can a lightning rod really be said to “attract” lightning?” – http://boards.straightdope.com/sdmb/showthread.php?t=274195