The line which marks approximately the southernmost place in the Northern Hemisphere where the sun does not set on the summer solstice and does not rise on the winter solstice
southern boundary of the North Frigid Zone which is situates south of the North Pole
The Arctic Circle is an imaginary line drawn around the northern part of the world at approximately 66° North. an imaginary line around the world at a particular distance from the most northern point, which is the North Pole Antarctic Circle. Parallel of latitude approximately
5° north of the Equator that circumscribes the northern frigid zone. It marks the southern limit of the area within which, for one day or more each year, the sun does not set or rise. The length of continuous day or night increases northward from the Arctic Circle, mounting to six months at the North Pole