I'm writing an in-house summary article on lightning for a fall semester class that's part of a weather unit. I've looked in a basic meteorology text and at (the ever-present) Wikipedia, and I'm a little puzzled by one aspect of a lightning strike. Here's what Wiki-P says:
"Once a conductive channel bridges the air between the negative charges in the cloud and the positive surface charges below, the flood gates are opened, and a massive electrical discharge follows. Neutralization of positive surface charges occurs first. An enormous current of positive charges races up the ionic channel towards the thundercloud."
Previous to this the Wiki-P article mentions the negatively charged bottom of the thunderhead inducing positive charge (which I take to mean the polarization of charge between surface and sub-surface) of the earth, but this "current of positive charges" racing upward has me puzzled. What are these positive charges, oxygen ions? This explanation sounds fishy/wrong to me, but I've never studied lightning or the literature about it. If someone has a better explanatory source, I would appreciate it.