St. Elmo’s fire is a stunning weather phenomenon in which electrical discharge from sharp or pointed objects creates plasma with a blue or violet glow. It typically happen during thunderstorms, when there’s a strong electric field in the atmosphere.
St. Elmo, or St. Erasmus of Formia, is the patron saint of sailors — a fitting name considering sailors would sometimes witness the phenomenon on ships at sea, taking it as a sign their patron saint was present. It also appears on aircraft wings, and in these pilots’ cases, right over the surface of their airliner’s windshield.