Static electricity builds up in the atmosphere due to charging of water, dust and gases present during thunderstorm. Saint Elmo’s phenomenon occurs when these charged particles find a communication to lower potential of earth. When the ionic plasma gets in touch with a sharp rod like surface it looses its energy by becoming neutralized. A blue light is emitted in the the wave like patterns with the contact point as the locus.
The phenomenon is named after Saint Erasmus of Formia. He is the patron saint of sailors. When the light streaks were observed over ship’s masts due to electric discharge during rough weather, sailors felt assured that saint is with them.
The phenomenon has been observed and recorded since historical times. Most notable and recent event happened with British Airways flight 009 while flying from Heathrow to Auckland via Mumbai, Kuala Lumpur, Sydney, Perth and Auckland. It happened during June 1982.
The sky over Malasya was covered with very fine volcanic ash due to volcanic activity in Indonesia. As the plane attained cruising height, it ran into the clouds of volcanic ash.
One by one it’s all four engines stalled. Pilot was a veteran and very cool minded. Calculating from the speed of descent and loss of altitude, the crew made plans to safely land it at some airport on the way or in the sea if the plan A doesn’t work.
Many passengers noticed saint Elmo’s fire over the engines. Pilots screen also underwent this phenomenon. As the plane came out of atmosphere of volcanic ash, dramatically all engines restarted. Airplane could gain altitude to cross a mountain range which was the cause of biggest worry.
Exactly what happened with plane was not saint Elmo’s fire alone, but the ash clogged the engines, and stalled them. It also marred the surface of pilot screen due to abrasion. The pilots couldn’t virtually see anything through screen.