Saint Elmo's fire, luminous discharge of electricity extending into the atmosphere from some projecting or elevated object. It is usually observed (often during a snowstorm or a dust storm) as brushlike fiery jets extending from the tips of a ship's mast or spar, a wing, propeller, or other part of an aircraft, a steeple, a mountain top, or even from blades of grass or horns of cattle. Sometimes it plays about the head of a person, causing a tingling sensation. The phenomenon occurs when the atmosphere becomes charged and an electrical potential strong enough to cause a discharge is created between an object and the air around it. The amount of electricity involved is not great enough to be dangerous. The appearance of St. Elmo's fire is regarded as a portent of bad weather. The phenomenon, also known as corposant, was long regarded with superstitious awe.