Arctic Circle
Overview
Circle of latitude
A circle of latitude, on the Earth, is an imaginary east-west circle connecting all locations that share a given latitude...
that mark maps of the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
. For Epoch 2011, it is the parallel of latitude
Latitude
In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...
that runs north of the Equator
Equator
An equator is the intersection of a sphere's surface with the plane perpendicular to the sphere's axis of rotation and containing the sphere's center of mass....
.
The region north of this circle is known as the Arctic
Arctic
The Arctic is a region located at the northern-most part of the Earth. The Arctic consists of the Arctic Ocean and parts of Canada, Russia, Greenland, the United States, Norway, Sweden, Finland, and Iceland. The Arctic region consists of a vast, ice-covered ocean, surrounded by treeless permafrost...
, and the zone just to the south is called the Northern Temperate Zone. The equivalent polar circle
Polar circle
A polar circle is either the Arctic Circle or the Antarctic Circle. On Earth, the Arctic Circle is located at a latitude of N, and the Antarctic Circle is located at a latitude of S....
in the Southern Hemisphere
Southern Hemisphere
The Southern Hemisphere is the part of Earth that lies south of the equator. The word hemisphere literally means 'half ball' or "half sphere"...
is called the Antarctic Circle
Antarctic Circle
The Antarctic Circle is one of the five major circles of latitude that mark maps of the Earth. For 2011, it is the parallel of latitude that runs south of the Equator.-Description:...
.
The Arctic Circle marks the extremity of the polar day
Midnight sun
The midnight sun is a natural phenomenon occurring in summer months at latitudes north and nearby to the south of the Arctic Circle, and south and nearby to the north of the Antarctic Circle where the sun remains visible at the local midnight. Given fair weather, the sun is visible for a continuous...
(24-hour sunlit day, often referred to as the "midnight sun") and polar night
Polar night
The polar night occurs when the night lasts for more than 24 hours. This occurs only inside the polar circles. The opposite phenomenon, the polar day, or midnight sun, occurs when the sun stays above the horizon for more than 24 hours.-Description:...
(24-hour sunless night).
Unanswered Questions
Encyclopedia
Circle of latitude
A circle of latitude, on the Earth, is an imaginary east-west circle connecting all locations that share a given latitude...
that mark maps of the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
. For Epoch 2011, it is the parallel of latitude
Latitude
In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...
that runs north of the Equator
Equator
An equator is the intersection of a sphere's surface with the plane perpendicular to the sphere's axis of rotation and containing the sphere's center of mass....
.
The region north of this circle is known as the Arctic
Arctic
The Arctic is a region located at the northern-most part of the Earth. The Arctic consists of the Arctic Ocean and parts of Canada, Russia, Greenland, the United States, Norway, Sweden, Finland, and Iceland. The Arctic region consists of a vast, ice-covered ocean, surrounded by treeless permafrost...
, and the zone just to the south is called the Northern Temperate Zone. The equivalent polar circle
Polar circle
A polar circle is either the Arctic Circle or the Antarctic Circle. On Earth, the Arctic Circle is located at a latitude of N, and the Antarctic Circle is located at a latitude of S....
in the Southern Hemisphere
Southern Hemisphere
The Southern Hemisphere is the part of Earth that lies south of the equator. The word hemisphere literally means 'half ball' or "half sphere"...
is called the Antarctic Circle
Antarctic Circle
The Antarctic Circle is one of the five major circles of latitude that mark maps of the Earth. For 2011, it is the parallel of latitude that runs south of the Equator.-Description:...
.
The Arctic Circle marks the extremity of the polar day
Midnight sun
The midnight sun is a natural phenomenon occurring in summer months at latitudes north and nearby to the south of the Arctic Circle, and south and nearby to the north of the Antarctic Circle where the sun remains visible at the local midnight. Given fair weather, the sun is visible for a continuous...
(24-hour sunlit day, often referred to as the "midnight sun") and polar night
Polar night
The polar night occurs when the night lasts for more than 24 hours. This occurs only inside the polar circles. The opposite phenomenon, the polar day, or midnight sun, occurs when the sun stays above the horizon for more than 24 hours.-Description:...
(24-hour sunless night). North of the Arctic Circle, the sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
is above the horizon
Horizon
The horizon is the apparent line that separates earth from sky, the line that divides all visible directions into two categories: those that intersect the Earth's surface, and those that do not. At many locations, the true horizon is obscured by trees, buildings, mountains, etc., and the resulting...
for 24 continuous hour
Hour
The hour is a unit of measurement of time. In modern usage, an hour comprises 60 minutes, or 3,600 seconds...
s at least once per year
Year
A year is the orbital period of the Earth moving around the Sun. For an observer on Earth, this corresponds to the period it takes the Sun to complete one course throughout the zodiac along the ecliptic....
and below the horizon for 24 continuous hours at least once per year. On the Arctic Circle those events occur, in principle, exactly once per year, at the June and December solstice
Solstice
A solstice is an astronomical event that happens twice each year when the Sun's apparent position in the sky, as viewed from Earth, reaches its northernmost or southernmost extremes...
s, respectively.
In fact, because of atmospheric refraction
Atmospheric refraction
Atmospheric refraction is the deviation of light or other things like humanelectromagnetic wave from a straight line as it passes through the atmosphere due to the variation in air density as a function of altitude...
and because the sun appears as a disk and not a point, part of the midnight sun may be seen on the night of the northern summer solstice
Summer solstice
The summer solstice occurs exactly when the axial tilt of a planet's semi-axis in a given hemisphere is most inclined towards the star that it orbits. Earth's maximum axial tilt to our star, the Sun, during a solstice is 23° 26'. Though the summer solstice is an instant in time, the term is also...
up to about 50′
Minute
A minute is a unit of measurement of time or of angle. The minute is a unit of time equal to 1/60th of an hour or 60 seconds. In the UTC time scale, a minute on rare occasions has 59 or 61 seconds; see leap second. The minute is not an SI unit; however, it is accepted for use with SI units...
(90 km (55.9 mi)) south of the Arctic Circle; similarly, on the day of the northern winter solstice
Winter solstice
Winter solstice may refer to:* Winter solstice, astronomical event* Winter Solstice , former band* Winter Solstice: North , seasonal songs* Winter Solstice , 2005 American film...
, part of the sun may be seen up to about 50′ north of the Arctic Circle. That is true at sea level; those limits increase with elevation above sea level although in mountainous regions, there is often no direct view of the true horizon.
The position of the Arctic Circle is not fixed, but directly depends on the Earth's axial tilt
Axial tilt
In astronomy, axial tilt is the angle between an object's rotational axis, and a line perpendicular to its orbital plane...
, which fluctuates within a margin of 2° over a 40,000 year period, notably due to tidal force
Tidal force
The tidal force is a secondary effect of the force of gravity and is responsible for the tides. It arises because the gravitational force per unit mass exerted on one body by a second body is not constant across its diameter, the side nearest to the second being more attracted by it than the side...
s resulting from the orbit of the Moon. The Arctic Circle is currently drifting northwards at a speed of about 15 m (49.2 ft) per year, see Circle of latitude for more information.
Geography
Relatively few people live north of the Arctic Circle due to the Arctic climateClimate of the Arctic
The climate of the Arctic is characterized by long, cold winters and short, cool summers. There is a large amount of variability in climate across the Arctic, but all regions experience extremes of solar radiation in both summer and winter...
. The three largest communities above the Arctic Circle are situated in Russia: Murmansk
Murmansk
Murmansk is a city and the administrative center of Murmansk Oblast, Russia. It serves as a seaport and is located in the extreme northwest part of Russia, on the Kola Bay, from the Barents Sea on the northern shore of the Kola Peninsula, not far from Russia's borders with Norway and Finland...
(population 325,100), Norilsk
Norilsk
Norilsk is an industrial city in Krasnoyarsk Krai, Russia, located between the Yenisei River and the Taymyr Peninsula. Population: It was granted city status in 1953. It is the northernmost city in Siberia and the world's second largest city north of the Arctic Circle...
(135,000), and Vorkuta
Vorkuta
Vorkuta is a coal-mining town in the Komi Republic, Russia, situated just north of the Arctic Circle in the Pechora coal basin at the Usa River. Population: - Labor camp origins :...
(85,000). Tromsø
Tromsø
Tromsø is a city and municipality in Troms county, Norway. The administrative centre of the municipality is the city of Tromsø.Tromsø city is the ninth largest urban area in Norway by population, and the seventh largest city in Norway by population...
(in Norway) has about 62,000 inhabitants. In contrast, the largest North American community north of the circle, Sisimiut
Sisimiut
Sisimiut is a town in central-western Greenland, located on the coast of Davis Strait, approximately north of Nuuk. It is the administrative center of the Qeqqata Municipality and the second-largest town in Greenland, with a population of 5,460 people as of 2010. The site of the present-day town...
(Greenland), has approximately 5,000 inhabitants, while between Canada and the USA, Barrow, Alaska
Barrow, Alaska
Barrow is the largest city of the North Slope Borough in the U.S. state of Alaska. It is one of the northernmost cities in the world and is the northernmost city in the United States of America, with nearby Point Barrow being the nation's northernmost point. Barrow's population was 4,212 at the...
is the largest settlement with circa 4,000 inhabitants. Rovaniemi
Rovaniemi
Rovaniemi is a city and municipality of Finland. It is the administrative capital and commercial centre of Finland's northernmost province, Lapland. It is situated close to the Arctic Circle and is between the hills of Ounasvaara and Korkalovaara, at the confluence of the Kemijoki River and its...
(in Finland), which lies slightly south of the line, has a population of approximately 58,000, and is the largest settlement in the immediate vicinity of the Arctic Circle.
The Arctic Circle passes through the Arctic Ocean
Arctic Ocean
The Arctic Ocean, located in the Northern Hemisphere and mostly in the Arctic north polar region, is the smallest and shallowest of the world's five major oceanic divisions...
, the Scandinavian Peninsula
Scandinavian Peninsula
The Scandinavian Peninsula is a peninsula in Northern Europe, which today covers Norway, Sweden, and most of northern Finland. Prior to the 17th and 18th centuries, large parts of the southern peninsula—including the core region of Scania from which the peninsula takes its name—were part of...
, North Asia
North Asia
North Asia or Northern Asia is a subregion of Asia, consisting of the Asian portion of Russia.The Phillips Illustrated Atlas of the World 1988 defines it as being most of the former USSR, the part that is to the east of the Ural Mountains...
, Northern America
Northern America
Northern America is the northernmost region of the Americas, and is part of the North American continent. It lies directly north of the region of Middle America; the land border between the two regions coincides with the border between the United States and Mexico...
and Greenland
Greenland
Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...
. The land on the Arctic Circle is divided among eight countries: Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
, Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....
, Finland
Finland
Finland , officially the Republic of Finland, is a Nordic country situated in the Fennoscandian region of Northern Europe. It is bordered by Sweden in the west, Norway in the north and Russia in the east, while Estonia lies to its south across the Gulf of Finland.Around 5.4 million people reside...
, Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
, the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
(Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
), Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
, Denmark
Denmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...
(Greenland
Greenland
Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...
), and Iceland
Iceland
Iceland , described as the Republic of Iceland, is a Nordic and European island country in the North Atlantic Ocean, on the Mid-Atlantic Ridge. Iceland also refers to the main island of the country, which contains almost all the population and almost all the land area. The country has a population...
(where it passes through the small offshore island of Grímsey
Grímsey
Grímsey is a small island in the country of Iceland, off the north coast of the main island of Iceland and straddling the Arctic Circle. In January 2011 it had 86 inhabitants....
).
Starting at the Prime Meridian
Prime Meridian
The Prime Meridian is the meridian at which the longitude is defined to be 0°.The Prime Meridian and its opposite the 180th meridian , which the International Date Line generally follows, form a great circle that divides the Earth into the Eastern and Western Hemispheres.An international...
and heading eastwards, the Arctic Circle passes through:
EWLINE
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See also
- Antarctic CircleAntarctic CircleThe Antarctic Circle is one of the five major circles of latitude that mark maps of the Earth. For 2011, it is the parallel of latitude that runs south of the Equator.-Description:...
- Arctic hazeArctic HazeArctic haze is the phenomenon of a visible reddish-brown haze in the atmosphere at high latitudes in the Arctic due to air pollution. A major distinguishing factor of Arctic haze is the ability of its chemical ingredients to persist in the atmosphere for an extended period of time compared to other...
- Scott Polar Research InstituteScott Polar Research InstituteThe Scott Polar Research Institute is a centre for research into the polar regions and glaciology worldwide. It is a sub-department of the Department of Geography in the University of Cambridge, located on Lensfield Road in the south of Cambridge ....
- Territorial claims in the ArcticTerritorial claims in the ArcticUnder international law, no country currently owns the North Pole or the region of the Arctic Ocean surrounding it. The five surrounding Arctic states, Russia, the United States, Canada, Norway and Denmark , are limited to an exclusive economic zone of adjacent to their coasts.Upon ratification...
- Tropic of CancerTropic of CancerThe Tropic of Cancer, also referred to as the Northern tropic, is the circle of latitude on the Earth that marks the most northerly position at which the Sun may appear directly overhead at its zenith...
- Tropic of CapricornTropic of CapricornThe Tropic of Capricorn, or Southern tropic, marks the most southerly latitude on the Earth at which the Sun can be directly overhead. This event occurs at the December solstice, when the southern hemisphere is tilted towards the Sun to its maximum extent.Tropic of Capricorn is one of the five...
- Arctic Cooperation and PoliticsArctic Cooperation and PoliticsArctic cooperation and politics are partially coordinated via the Arctic Council, composed of the eight Arctic nations of the United States of America, Canada, Iceland, Norway, Sweden, Finland, Russia, and Denmark with Greenland and The Faroe Islands...
- Circumpolar Circle
External links
- Terra Incognita: Exploration of the Canadian Arctic—Historical essay about early expeditions to the Canadian Arctic, illustrated with maps, photographs and drawings
- Temporal Epoch Calculations ©2006 by James Q. Jacobs Download: Epoch v2009.xls (modify D4)
- Useful constants" See: Obliquity of the ecliptic
- ArcticFocus Facts and news about Arctic Documentaries and films about Arctic and Inuit