One hundred lightning bolts strike Earth’s surface every second, each containing up to one billion volts of electricity. Cloud-to-ground lightning is caused by an electrical imbalance: precipitation collects at the base of storm clouds and creates a negative charge, while objects on the ground become positively charge—and nature remedies the imbalance by passing an enormous electrical current between them. Lightning actually moves in steps that work their way down to Earth with incredible speed, creating a fractal pattern—then the lowermost step is met by a surge of positive electricity from the target below, and electricity is channelled through as lightning. This surge can climb through a tree, a building, or even a person, so it’s unsurprisingly that approximately 2,000 people are killed by lightning each year. The lucky ones who survive being struckare sometimes left with remarkable fractal scarring on their skin, called Lichtenberg figures or “lightning trees”. Lichtenberg figures were discovered by German physicist Georg Christoph Lichtenberg, who found that when an electrical discharge strikes insulating material, it’s reproduced on the surface or interior of the material. It looks like trapped lightning because it quite literally is, showing the fascinating pattern of the branching steps. It’s not the heat that causes the scarring, however; it’s hypothesized that the shockwave of the lightning current ruptures capillaries under the skin. Since they’re not burns, Lichtenberg figures generally only last from a few hours to a few days before fading from the skin.