Északisarkkör

Északisarkkör refers to the Arctic Circle, one of the Earth's five major circles of latitude. It is located at 66°33′46.2″ North latitude. This line of latitude marks the southernmost point in the Arctic region where the sun remains continuously above the horizon for 24 hours at least once during the summer solstice and continuously below the horizon for 24 hours at least once during the winter solstice.

The region north of the Arctic Circle is known as the Arctic. The phenomenon of the midnight sun occurs during the summer months within this region, where daylight lasts for 24 hours. Conversely, the polar night takes place during the winter, when the sun does not rise for extended periods. The exact position of the Arctic Circle is not fixed; it fluctuates slowly over time due to variations in the Earth's axial tilt.

Several countries have territory that lies within or crosses the Arctic Circle, including Norway, Sweden, Finland, Russia, the United States (Alaska), Canada, and Denmark (Greenland). The landscape north of the Arctic Circle is characterized by tundra, ice caps, and glaciers. Human populations in this region are sparse, with indigenous peoples having adapted to the harsh climate for centuries. The Arctic Circle is a significant geographical and climatic boundary, influencing weather patterns and ecosystems across the Northern Hemisphere.