Corona discharge Corona discharge A corona discharge is an electrical discharge brought on by the ionization of a fluid such as air surrounding a conductor that is electrically charged. Spontaneous corona discharges occur naturally in high-voltage systems unless care is taken to limit the electric field strength. A corona will occur when the strength of the electric field (potential gradient) around a conductor is high enough to form a conductive region, but not high enough to cause electrical breakdown or arcing to nearby objects. It is often seen as a bluish (or other color) glow in the air adjacent to pointed metal
Collis (planetary nomenclature) Collis (planetary nomenclature) Collis (plural: colles, from the Latin word for "hill") is a small hill or knob on a celestial body. The term is used in planetary nomenclature: it is a part of international proper names of such features. Like other generic terms, it is capitalized and stands after the proper name (for example, "Bilbo Colles"; the only exception is "Colles Nili" on Mars). As of 2015, only groups of the hills have names, and the term is used only in plural. Like the other terms of planetary nomenclature, this word describes only external view of the features, but