"Arctic Circle." YourDictionary, n.d. Web. 15 October 2018. <http://www.yourdictionary.com/arctic-circle>.
Arctic Circle. (n.d.). Retrieved October 15th, 2018, from http://www.yourdictionary.com/arctic-circle
The parallel of latitude approximately 66°34&minute; north, the southern boundary of the North Frigid Zone, marking the approximate limit north of which the sun remains above the horizon all day on the summer solstice.