If you've ever seen a Frankenstein movie you have probably seen a Jabcobs Ladder. The familliar "Bzzzzzzzzzzz....snap!" sound is a staple of old horror movies.
So how do they work? At the base of the "V" shaped rails, a sufficient voltage is provided to breakdown and ionize the air. The electricity jumps the gap, and if there is enough current, creates a very hot ionized air channel resembling a flame. Convection carries this channel upwards, and since it conducts better than the surrounding air, the arc gets longer and longer as it moves upwards. Eventually the arc rises to a point where the rails are so far apart that it cannot sustain itself. It then goes out and starts again at the bottom.
