Whenever you have two electrical conductors near each other, but not touching, you have a capacitor. Electrical transmission lines are obviously conductive, bu

Whenever you have two electrical conductors near each other, but not touching, you have a capacitor. Electrical transmission lines are obviously conductive, but so is the earth, with its large amounts of metal and salt water. When extra electrons collect in the transmission lines[1], they become negatively charged and repel electrons on the surface of the earth, leaving unpaired protons and a positive charge there. As there are two oppositely charged objects in proximity to each other, an attractive force exists between them. This force is generally referred to in terms of voltage because it’s very small in absolute terms, but electrons are also very light and thus strongly affected. The electrons can’t make it across the gap to the positively-charged Earth, however, because air is an insulator. That means that all of its protons and electrons are bound tightly to each other, so there’s no intermediate place for the electrons in the wire to jump to, and they have to make it all the way across the gap in one go, which is extremely unlikely. By driving a metal stake into the ground, you’ve provided a path along which the electrons can move little at a time in the direction that the electrical force is pulling them. When they arrive, they’ll pair up with a proton and reduce the attractive force a little bit. Over time, this prevents the large buildups that can become dangerous. [1] Electrical storms and lightning strikes are the most dramatic causes, but not the only ones.