Unusual Twilight Phenomena in Europe
Between August 21 and September 3, 2017, unusual twilight phenomena could be observed in widespread parts of Germany. In most cases, the sky turned into a bright yellow short after sunset. Some observers reported an increase of brightness when this yellow glow appeared. During the following 20 minutes, the colour changed into orange and later into red with the coloured part of the sky shrinking towards the western horizon. At the end, only a narrow red stripe directly above the horizon remained. Additionally, there was a very intense purple light even during the “orange phase”. Many observers reported that the landscape also appeared in a bright yellow or orange coloured light.
At daytime, the sky appeared in a pale blue as if there was a layer of thin cirrostratus clouds. At low sun elevations, stripes and ripples appeared in this layer. Some observers felt reminded of noctilucent clouds by these structures.
In the mornings, these phenomena also appeared in reversed order.
Similar phenomena were also reported from observers in Austria, Hungary, the United Kingdom, Danmark and Iceland and showed up in several pictures by webcams in the Czech Republic.
More pictures and time lapses (e.g. 1–2) you can find in the Forum of “Arbeitskreis Meteore e.V.
These strange twilight phenomena were caused by the smoke of huge wildfires in Canada. The plumes of these fires ascended up to the stratosphere reaching altitudes of about 15 kilometres. Then they were transported over the Atlantic Ocean by the wind.
When travelling through the northeastern parts of the USA to observe the total solar eclipse which ocurred on August 21, Andreas Möller could take photographs of these plumes of smoke.
Author: Peter Krämer, Bochum, Germany