In the current article the author allots a task to observe several plots from Dark Age Scandinavian history using the «new tools» of historian – researching the weather conditions, climate changes and natural cataclysms happened in the past. The main aim is the uncovering of possible connection between wide-known «volcanic winter» of 535–536 A.D., the development of herulic power in Middle Sweden (in the vaster territories later) and the emergence of Ragnarok myth concerned with the mindset changes.