If you heard a strange crackling noise, went outside, and noticed what seemed to be lightning attacking parts of your building, what would you do? One man took a picture.
Sonnblick Observatory in Austria serves as a focus for the famous St. Elmo’s Fire. Hermann Scheer, who snapped this picture, describes it as being a snowy day, but without any thunderstorm activity.
Clearly something was brewing. St. Elmo’s Fire is one of the things that happens when plasma lights up. Plasma consists of gas atoms that have their outer electrons stripped off, either by an extreme electric field or by extreme heat. The electrons go wandering freely through the gas, which means that the gas is now a very good conductor of electricity. Unlike things like fire or lightning (both of which have plasma components), St. Elmo’s Fire can be fairly cool. It was known for gathering around wooden ship’s masts without setting them on fire.
St. Elmo’s Fire needs a major voltage difference, and so it tends to gather around points and corners, where the voltage difference is most dramatic. (This is also why lightning tends to strike at the tips of rods or trees.) As you can see in the picture, it’s gathered around the two most dramatic curves on the building.
Via AT Optics.
