Question

explain why St. Elmo’s fire is observed at the ends of sharply pointed exterior surfaces of aircraft such as wing tips and propellers. Be sure to explain why St. Elmo’s fire is not observed on surfaces that are flat or on interior parts of the aircraft.

Answer 1

St. Elmo's fire is an ionized plasma that glows.When an aircraft flys through the air, it passed through clouds and other air moluecules that charge it. This charging is due to the ions present in the air. Now, these this ions accumulate on the metal surface of the aircraft over time. With time these ions get discharged from the metal surface using corona discharge. Cornona discharge is the dicharge of electrical charge when there is a signigicant imbalance of the charge in the metal and surrounding. The charge tends to leave the metel through a pointy surface causing a fire like illuminance and hissing sound. The pointy surface makes it much easier to discharge from a single point of the conductor. In our case it is the pointy tips of wing and propellers exterior surfaces of aircraft. Flat surfaces or interior do no posses such properties hence it do not glows.