For most of human history, people have been terrified by lightning. Frightening bolts from above, lightning was a tool of the gods to smite mortals for their hubris (or their unfortunate penchant for seeking shelter from storms under trees). The discovery and implementation of Benjamin Franklin’s lightning rod tamed this once formidable, divine weapon.
Nonetheless, lightning’s strength still lingers in our imagination. Hollywood considers it powerful enough to allow strangely designed cars from the early 1980s to break the space-time continuum. In the comic book world, it’s an ingredient in the formula for developing superpowers. It has also been given the power to return life to the dead, though not always with the intended effect.
Just how much energy actually is in a lightning bolt? It may seem like this question should have been definitively answered before, but it turns out it’s difficult to answer quantitatively. In my research, we tackled this issue in a new way: We deduced how big a bolt of lightning was based on the size of rocks formed by lightning.
Lightning is obviously powerful: One need only look at a tree that it’s splintered down the center for proof. Lightning generates temperatures hotter than the surface of the sun, in excess of 20,000 degrees Celsius, a temperature that is otherwise unrelateable to the human experience.
This temperature measurement provides one way to estimate the energy of lightning. It takes a certain amount of energy to heat air to a high temperature. By measuring the length of a lightning strike, multiplying it by the energy per length required to heat up the air to tens of thousands of degrees, we can calculate lightning’s energy.