The number of days the sun stays above(or below) the horizon increases the farther north one goes until, at the pole, the sun never sets for 6 months and never rises during the other 6. These effects occur because the Earth's axis of rotation is tilted relative to the plane of its orbit around the sun.
During the northern winter, when the Northern Hemisphere is tilted away from the sun, the Earth's curvature creates an area of permanent shadow centred on the North Pole. This area starts to form at the fall equinox (September 22), grows to a maximum at midwinter, then decreases, vanishing by the spring equinox (March 21). For the remainder of the year, when the northern hemisphere is tilted towards the sun, an area of permanent sunlight centres on the pole. Because the tilt of the Earth's axis is about 23.5°, the Arctic and Antarctic circles lie at latitudes of about 66.5°.
The Arctic Circle is not a climatic boundary. Trees grow north of it in the Mackenzie Delta; in Nouveau-Québec the TREELINE is 1000 km farther S. INUVIK, NWT, is the only moderately large Canadian settlement lying north of the circle.
Author W.S.B. PATERSON
Links to Other Sites
Search the extensive "Images Canada" site for historical images depicting the people and landscape of Canada’s Arctic.
North Circumpolar Region
View a map of the Arctic region from a vantage point above the North Pole. From the Perry-Castañeda Library Map Collection at the University of Texas.
In this website you will find several animations designed and produced by the International Polar Foundation on different topics linked to the polar regions, the way our planet's climate functions, climate change and energy.