Saint Elmo's Fire
(Section 3.2.4.2)Definition: Saint Elmo's fire: A more or less continuous, luminous electrical discharge of weak or moderate intensity in the atmosphere, emanating from elevated objects at the Earth’s surface (for example, lightning conductors, wind vanes and ship masts) or from in-flight aircraft (for example, wing tips).
This phenomenon may be observed when the electrical field near the surface of objects becomes strong. It often appears in the form of violet or greenish plumes or egrets, clearly visible at night.
While the electrical conditions that generate Saint Elmo's fire exist in association with thunderstorms, it may also develop in electric fields enhanced by heavy snow and strong wind without thunderstorms, and with aircraft flying through volcanic ash.