The Winterfire-term refers to stock footage which displays Northern Lights or Aurora Borealis in many of it’s forms, shot in timelapse-format.
Northern Lights or Aurora Borealis are produced when charged particles are blasted out from the sun, which then excite particles in the Earth’s upper atmosphere. The upper atmosphere’s particles emit photons when returning from the excited states to normal states, which are then seen as the Northern Lights.
Especially in the northern people’s folklore, Northern Lights have their own part. For example the native people of Lapland, the Sami people, believe, that the Northern Lights are blood spilt from the fighters who ensue battles in the heavens, or that people in the heavens cut themselves which is then seen as dancing lights. The Norse people believed, that the armor of the Valkyries, creatures who carried the valiant dead from the battlefield to Valhalla, glimmered as they rode across the northern nightsky.
Explanation of different Winterfire-products: