Active aurora band - 27.3.2019 at 20.15 - 27.3.2019 at 22.20 Inari Observation number 82254

Copyright © 2019 Minna Glad. All rights reserved.

Visibility III / V

Minna Glad, Kuopion Saturnus

20.3. the departed CME didn’t even offer a spectacle to watch, but luckily the corona opening became a little trickle in the sky for the following evenings - and at the height of Lake Inari it was supposed to see even something anyway.

The northern sky was still light, but in the eastern horizon the head of the northern lights arc began to stand out more than eight quarters. After a few minutes, two arches were already visible, the upper of which was dimmer. At 20:19 - 20:22 a bright attack from east to west progressed along the lower arch. From 20:30 to 20:45 the arc barely faded to stand out. Then several west-moving brightnesses appeared (pictured), which after about five minutes had developed into high rays. The arc continued to vary, dimming, brightening, and providing rays, and the dim corona was also visible at least at 9 p.m. and 9:20 p.m. A quarter of a dozen northern rays danced to dim rays up to a height of about 45 degrees. At ten to ten, the view had changed to a triple arc (pictured). It twisted into the folds that moved west. Then the arc descended closer to the horizon but remained bright, and the zenith showed a constant movement of dim curves! They moved from north to south in a continuous series, following each other every 1-3 seconds like waves. This lasted at least from 9:50 pm to 10:10 pm, maybe even longer. There was no northern fire south of them. The movement was only visible above the head, so I don’t know if it happened in other parts of the oval as well. The last picture shows the situation to the east just before I noticed this “wave effect”. I didn’t get a picture of the ripple itself to succeed.

This description has been automatically translated from Finnish. Click here to see the original text.

10 11

Additional information

Aurora brightness
- Dim auroras
Observed aurora forms
- Rays
  
  The raysare parallel to the lines of force of the magnetic field, i.e. quite vertical, usually less than one degree thick light streaks. The rays can occur alone or in connection with other shapes, mainly with arcs and bands. Short rays are usually brightest at the bottom but dim quickly. The longest rays, even extending almost from the horizon to the zenith, are usually uniformly bright and quite calm, and unlike the shorter rays, most often occur in groups of a few rays or alone. Rays, like bands, are a very typical form of aurora.
  
  Artificial light pillars, which are a halo phenomenon visible in ice mist, can sometimes be very similar to the rays of aurora. Confusion is possible especially when the lamps that cause the artificial light pillars are far away and not visible behind buildings or the forest. The nature of the phenomenon is clear at least from the photographs.
  
  Rays. Picture of Tom Eklund.
  
  Rays. Photo by Mika Puurula.
  
  Two beams rise from the aurora veil. Photo by Anssi Mäntylä.
  
  Two radial bands. Show Jani Lauanne.
  
  Radial band and veil. Photo by Jussi Alanenpää.
  
  Two rays. Photo by Aki Taavitsainen.
  
  It may be possible to confuse such rays with artificial light columns. Compare the image below. Picture of Tom Eklund.
  
  There is no aurora in this image, but all the light poles - including the wide and diffuse bar seen at the top left - are artificial light pillars born of ice mist. Photo by Sami Jumppanen.
  
  Aurora and artificial light pillars. All the radial shapes in the picture above are probably artificial light pillars that coincide appropriately with the aurora band. In the image below, the aurora band has shifted and does not overlap with the pillars produced by the orange bulbs. There is no orange in auroras. Photo by Katariina Roiha
- Band
  
  Bands are usually narrower, more twisty at the bottom, brighter, and more active than arches. Bands usually develop from arches.
  
  Bands can form J and U shapes, sometimes even full spirals. The corona can also arise from bands. Bands are a fairly common form of aurora.
  
  Aurora band. Photo by Merja Ruotsalainen.
  
  Aurora band. Photo by Matias Takala.
  
  Aurora band. Photo by Lea Rahtu-Korpela.
  
  Aurora bands. Photo by Lauri Koivuluoma.
  
  Aurora band. Photo by Matias Takala.
- Corona
  
  CoronaA corona is a hand fan shaped structure, it usually forms south of the observer's zenith, most commonly consisting of rays or bands. The corona is usually the most beautiful part of the aurora show. It is bright and active, but on the other hand also short-lived.
  
  Aurora corona. Photo by Anna-Liisa Sarajärvi.
  
  Aurora corona. Photo by Merja Ruotsalainen.
  
  Corona formed from bands. Photo by Markku Ruonala.
  
  Aurora corona. Photo by Tapio Koski.
- Arc
  
  ARC The arcs are wider than the bands and do not fold as strongly. The arcs are normally neither very bright nor active.
  
  The arc is probably the most common form of aurora. When aurora show is a calm arc in the low northern sky it often doesn’t evolve to anything more during night. In more active shows the arc is often the first form to appear and the last to disappear.
  
  The lower edge of the arc is usually sharp but the upper edge can gradually blend into the background sky. As activity increases rays and folds normally develop, and the arcs turn gradually into bands.
  
  An aurora arc runs across the picture. Vertical shapes are rays. Photo by Atacan Ergin.
  
  Aurora Arc. Photo by Mauri Korpi.
  
  Aurora Arc. Photo by Anna-Liisa Sarajärvi.
  
  Aurora Arc. Photo by Matti Asumalahti.

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