St. Elmo's Fire is an electrical discharge observed around masts, poles, and spires causing ionisation of the surrounding atmosphere. It often produces crackling noises as well as giving rise to luminous displays often described as fireworks, jets, stars, corona, streams, or sparking. St. Elmo's Fire can cause radio disturbances, but is often taken to be a good sign, because it occurs at the end of thunderstorms, hence signifying clearer weather to come. As St. Elmo is the patron saint of sailors, the sailors took it to be a sign of St. Elmo appearing to them, and gave it its common name.
The coronal discharge is often refered to as the corposant—from the Old Spanish corpo santo, i.e. holy, or saint's, body—the oldest reference for which in the OED is Eden's Arte of Nauigation (1561), where he speaks of "［s］hining exhalations that appeare in tempestes: whiche the Mariners call san…
