St. Elmo’ fire is a luminous plasma resulting from a discharge from pointed objects (like a mast, animal horn, or a chimney) or occasionally the leading edges of airplanes. The plasma is generally brushlike in appearance and blue or violet in color. It also occurs in the shape of a lightning over the windshields of airplanes, and a hissing sound accompanies the plasma. It is mostly noticable in stormy weathers.
St. Elmo’s fire takes its name after St. Erasmus of Formia, the patron saint of sailors. Therefore, sailors interpreted the phenomenon as a good omen as well as a sign of guardianship over them.