STEVE (a different aurora)
On the evening of January 17, 2013 there was a vivid display of aurora borealis as seen from my location in Ørsta, Norway. (Lat 62.18 N). (Please, see two images at the bottom of this page).
The same evening, I also noticed a structure – a band, that resembled a contrail from a plane. This narrow band was however different. It appeared white, but a tint glow of purple could be seen. I stopped photographing the aurora borealis, and directed the camera/lens to the eastern sky where the phenomenon was located. And shot several images. The photographic field was not wide enough to cover the band in one shot. Here is a panorama version (two photos combined into one image).
Several years later, in 2016, this phenomenon was named STEVE.
STEVE, is an abbreviation for: Strong Thermal Emission Velocity Enhancement.
It is a phenomenon that is still not fully understood, and research is ongoing.
Recent research tells us that:
STEVE’s seem to form from a ribbon of hot gases rather than from streaming electrons and protons that create (most) auroras.
STEVE is purple (or mauve) in color (occasionally, a green “picket-fence” occurs below), and takes shape in a narrow arc below and equatorward of the primary auroral band. STEVE is almost always aligned in an east-west direction. According to observations the phenomenon can stretch out for hundreds or even thousands of km.
STEVE is a phenomenon caused by a stream of fast and extremely hot particles, called a sub-auroral displacement of ions.
STEVE is seen on lower latitudes than ordinary polar lights.
Carl Størmer photographed STEVE over Oslo, Norway in 1911. He called the phenomenon “feeble homogenous arcs of great altitude”.
(Please, see links for more elaborate resources at the very bottom of this page)
Link to resources: