St. Elmo's fire

St. Elmo's fire, also known as corposant, is the glowing electrical discharge seen at the tips of tall, pointed objects – church spires, ship's masts, airplane wings, etc. – in stormy weather. The negative electrical charge on the storm clouds induces a positive charge on the tall structure. The impressive display is named (corruptly) for St. Erasmus, patron saint of sailors.