Definitions for "Arctic Circle"
The line of latitude 66°34′N (often taken as 66 Along this line the sun does not set on the day of the summer solstice, about June 21, and does not rise on the day of the winter solstice, about December 22. From this line the number of twenty- four-hour periods of continuous day or of continuous night increases northward to about six months each at the North Pole.
The parallel of latitude approximately 66°30' north. It forms the boundary between the North Temperate and North Frigid zones. This parallel marks the southern limit of the area within which for at least one day each year the Sun does not set (about June 21st) or rise (about December 21st).
parallel of latitude at 66°N