Why the Northern lights may appear contrary to all forecasts?

Sometimes polar auroras no much to do with forecasts of space weather. On the night of October 20 was predicted relatively calm conditions near the Arctic circle — only 10 % probability of geomagnetic storms. However, when Alan Dyer raised his eyes to heaven, standing on the moonlit deck of the Norwegian cruise ship, the Trollfjord, here is what he saw:

According to him, when the ship crossed the Barents sea along the Arctic coast of Norway, in the sky suddenly played great flashes. At the same time, officially, the Kp index (geomagnetic activity index) was 0!

The Barents sea is a special place where auroras can appear even at weak solar activity. The sea is under constant auroral oval of our planet, the ring-shaped region surrounding the North pole, where the geomagnetic field directs particles from space down into the upper layers of the atmosphere. Inside this oval can suddenly appear the Aurora, leaving the sky an incredible "splash" of green and purple light and no solar storms is not required for this.

"Trollfjord is one of the ferries on the Norwegian coast and provides excellent opportunities for viewing the Northern lights, adds Dyer. Yesterday's "show" is an example of polar auroras, which are always present at high latitudes under the oval, in spite of low solar activity."

Translated by «Yandex.Translator»