St. Elmo's fire

St. Elmo's fire (also called corposant, Hermes fire, furole, witchfire or witch's fire) is a <a href="/facts/Glossary_of_meteorology/LQzkjgWv">weather phenomenon</a> in which luminous <a href="/facts/Plasma_(physics)/1d3btMVU">plasma</a> is created by a <a href="/facts/Corona_discharge/caQ4gmoP">corona discharge</a> from a rod-like object such as a <a href="/facts/Mast_(sailing)/fA4p9N56">mast</a>, spire, chimney, or animal horn in an atmospheric <a href="/facts/Electric_field/tt4MooBs">electric field</a>. It has also been observed on the leading edges of aircraft, as in the case of <a href="/facts/British_Airways_Flight_009/xA6u6eTn">British Airways Flight 009</a>, and by US Air Force pilots. 
The intensity of the effect, a blue or violet glow around the object, often accompanied by a hissing or buzzing sound, is proportional to the strength of the electric field and therefore noticeable primarily during <a href="/facts/Thunderstorm/F6hUzuAu">thunderstorms</a> or <a href="/facts/Volcanic_eruption/AwqpzdaG">volcanic eruptions</a>.
St. Elmo's fire is named after St. <a href="/facts/Erasmus_of_Formia/ANq6DjcL">Erasmus of Formia</a> (also known as St. Elmo), the <a href="/facts/Patron_saint/Gw1cv1vH">patron saint</a> of sailors. The phenomenon, which can warn of an imminent <a href="/facts/Lightning_strike/YFXlRMKp">lightning strike</a>, was regarded by sailors with awe and sometimes considered to be a good omen.

St. Elmo's fire open-in-new

St. Elmo's fire