An Elms fire at Sonnblick Observatory on 29.10.2018 at 19:30! It pays off to look at the time lapse -> Link: https://www.foto-webcam.eu/webcam/sonnblick/2018/10/29/1930
What is an Elms fire?
An Elms fire (Saint Elms fire, Elias fire) is a rare light phenomenon (electric meteors) caused by electrical charges. It is named after the canonized Bishop Erasmus of Antioch (c. 240-303, Italian Elmo), whom sailors called in case of a storm.
An Elms fire is a continuous corona discharge in the atmosphere that occurs in thunderstorm weather conditions with electric field strengths higher than 100 kV / m. The Elms fire can be observed under these conditions on high, pointed objects, such as ship masts, church towers, mountain peaks and wire fences. It also occurs on windshields of aircraft.
Even in the mountains, in case of an approaching thunderstorm, this weather phenomenon can occur. Especially in the area of the summit cross it can come to these phenomena, coupled with a characteristic humming.
Elms fire causes an immediate danger of lightning. The Elms fire light is blue-violet due to the spectral lines of the gases oxygen and nitrogen in the earth atmosphere.
Source german: https://de.wikipedia.org/wiki/Elmsfeuer
Here is a video by Hermann Scheer from 2013: https://www.youtube.com/watch?v=d61PWg_dQjU.
There were monitored a couple of Elms fire at the Sonnblick Observatory. An example in 2012 is shown by MSc.-Met. Sebastian Schappert (German Weather Service): https://www.dwd.de/DE/wetter/thema_des_tages/2018/6/26.html