North Pole in the context of "Water sky"

The Northern Hemisphere is the half of Earth that is north of the equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the Solar System as Earth's North Pole.

Due to Earth's axial tilt of 23.439281°, there is a seasonal variation in the lengths of the day and night. There is also a seasonal variation in temperatures, which lags the variation in day and night. Conventionally, winter in the Northern Hemisphere is taken as the period from the December solstice (typically December 21 UTC) to the March equinox (typically March 20 UTC), while summer is taken as the period from the June solstice through to the September equinox (typically on 23 September UTC). The dates vary each year due to the difference between the calendar year and the astronomical year. Within the Northern Hemisphere, oceanic currents can change the weather patterns that affect many factors within the north coast. Such events include El Niño–Southern Oscillation.

The Arctic Ocean is the smallest and shallowest of the world's five oceanic divisions. It spans an area of approximately 14,060,000 km (5,430,000 sq mi) and is the coldest of the world's oceans. The International Hydrographic Organization (IHO) recognizes it as an ocean, although some oceanographers call it the Arctic Mediterranean Sea or North Polar Sea. It has also been described as an estuary of the Atlantic Ocean. It is also seen as the northernmost part of the all-encompassing world ocean.

The Arctic Ocean includes the North Pole region in the middle of the Northern Hemisphere and extends south to about 60°N. The Arctic Ocean is surrounded by Eurasia and North America, and the borders follow topographic features: the Bering Strait on the Pacific side and the Greenland Scotland Ridge on the Atlantic side. It is mostly covered by sea ice throughout the year and almost completely in winter. The Arctic Ocean's surface temperature and salinity vary seasonally as the ice cover melts and freezes; its salinity is the lowest on average of the five major oceans, due to low evaporation, heavy fresh water inflow from rivers and streams, and limited connection and outflow to surrounding oceanic waters with higher salinities. The summer shrinking of the ice has been quoted at 50%. The US National Snow and Ice Data Center (NSIDC) uses satellite data to provide a daily record of Arctic sea ice cover and the rate of melting compared to an average period and specific past years, showing a continuous decline in sea ice extent. In September 2012, the Arctic ice extent reached a new record minimum. Compared to the average extent (1979–2000), the sea ice had diminished by 49%.

The Danish Realm, officially the Kingdom of Denmark, or simply Denmark, is a sovereign state consisting of a collection of constituent territories united by the Constitutional Act, which applies to the entire territory. It consists of metropolitan Denmark (sometimes called "Denmark proper")—the kingdom's territory in continental Europe and its proximate islands—and the realm's two autonomous (but not sovereign) regions: the Faroe Islands in the North Atlantic and Greenland in North America. The relationship between the three parts of the kingdom is known as rigsfællesskabet (the unity of the realm, which has also been translated into the Danish Commonwealth or the United Kingdom of Denmark).

The Kingdom of Denmark is not a federation, but a concept encompassing the three autonomous legal systems of Denmark, the Faroe Islands and Greenland, united under its monarch. The Kingdom of Denmark is a unitary sovereign state. It has Arctic territorial claims in the Arctic Ocean: various sites near the North Pole (Lomonosov Ridge, Gakkel Ridge, and the Alpha-Mendeleev Ridge complex). The Kingdom of Denmark constitutionally encompasses the realm or the country, but the Faroe Islands and Greenland have an extended degree of autonomy to govern their relations.

The equator is the circle of latitude that divides Earth into the Northern and Southern hemispheres. It is an imaginary line located at 0 degrees latitude, about 40,075 km (24,901 mi) in circumference, halfway between the North and South poles. The term can also be used for any other celestial body that is roughly spherical.

In spatial (3D) geometry, as applied in astronomy, the equator of a rotating spheroid (such as a planet) is the parallel (circle of latitude) at which latitude is defined to be 0°. It is an imaginary line on the spheroid, equidistant from its poles, dividing it into northern and southern hemispheres. In other words, it is the intersection of the spheroid with the plane perpendicular to its axis of rotation and midway between its geographical poles.

The International Date Line (IDL) is the line extending between the South and North Poles that is the boundary between one calendar day and the next. It passes through the Pacific Ocean, roughly following the 180.0° line of longitude and deviating to pass around some territories and island groups. Crossing the date line eastbound decreases the date by one day, while crossing the date line westbound increases the date.

The line is a cartographic convention and is not defined by international law. This has made it difficult for cartographers to agree on its precise course and has allowed countries through whose waters it passes to move it at times for their convenience.

The meridian 23° east of Greenwich is a line of longitude that extends from the North Pole across the Arctic Ocean, the Atlantic Ocean, Europe, Africa, the Indian Ocean, the Southern Ocean, and Antarctica to the South Pole.

The 23rd meridian east forms a great circle with the 157th meridian west.

In geography, latitude is a geographic coordinate that specifies the north-south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from −90° at the south pole to 90° at the north pole, with 0° at the Equator. Lines of constant latitude, or parallels, run east-west as circles parallel to the equator. Latitude and longitude are used together as a coordinate pair to specify a location on the surface of the Earth.

On its own, the term latitude normally refers to the geodetic latitude as defined below. Briefly, the geodetic latitude of a point is the angle formed between the vector perpendicular (or normal) to the ellipsoidal surface from the point, and the plane of the equator.

The polar regions, also called the frigid zones or polar zones, of Earth are Earth's polar ice caps, the regions of the planet that surround its geographical poles (the North Pole and the South Pole), lying within the polar circles. These high latitudes are dominated by floating sea ice covering much of the Arctic Ocean in the north, and by the Antarctic ice sheet on the continent of Antarctica and the Southern Ocean in the south.

The north and south celestial poles are the two points in the sky where Earth's axis of rotation, indefinitely extended, intersects the celestial sphere. The north and south celestial poles appear permanently directly overhead to observers at Earth's North Pole and South Pole, respectively. As Earth spins on its axis, the two celestial poles remain fixed in the sky, and all other celestial points appear to rotate around them, completing one circuit per day (strictly, per sidereal day).

The celestial poles are also the poles of the celestial equatorial coordinate system, meaning they have declinations of +90 degrees and −90 degrees (for the north and south celestial poles, respectively). Despite their apparently fixed positions, the celestial poles in the long term do not actually remain permanently fixed against the background of the stars. Because of a phenomenon known as the precession of the equinoxes, the poles trace out circles on the celestial sphere, with a period of about 25,700 years. The Earth's axis is also subject to other complex motions which cause the celestial poles to shift slightly over cycles of varying lengths (see nutation, polar motion and axial tilt). Finally, over very long periods the positions of the stars themselves change, because of the stars' proper motions. To take into account such movement, celestial pole definitions come with an epoch to specify the date of the rotation axis; J2000.0 is the current standard.

A geographical pole or geographic pole is either of the two points on Earth where its axis of rotation intersects its surface. The North Pole lies in the Arctic Ocean while the South Pole is in Antarctica. North and South poles are also defined for other planets or satellites in the Solar System, with a North pole being on the same side of the invariable plane as Earth's North pole.

Relative to Earth's surface, the geographic poles move by a few metres over periods of a few years. This is a combination of Chandler wobble, a free oscillation with a period of about 433 days; an annual motion responding to seasonal movements of air and water masses; and an irregular drift towards the 80th west meridian. As cartography and geodesy require exact and unchanging coordinates, the average or nominal locations of geographical poles are taken as fixed cartographic poles or geodetic poles, the points where the body's great circles of longitude intersect; in practice this is achieved by keeping latitude values of survey markers fixed and accounting for time variations in terms of Earth orientation parameters.

The history of exploration by citizens or subjects of the Russian Federation, the Soviet Union, the Russian Empire, the Tsardom of Russia and other Russian predecessor states forms a significant part of the history of Russia as well as the history of the world. At 17,075,400 square kilometres (6,592,850 sq mi), Russia is the largest country in the world, covering more than a ninth of Earth's landmass. In the times of the Soviet Union and the Russian Empire, the country's share in the world's landmass reached 1/6. Most of these territories were first discovered by Russian explorers (if indigenous peoples of inhabited territories are not counted). Contiguous exploration in Eurasia and the building of overseas colonies in Russian America were some of the primary factors in Russian territorial expansion.

Apart from their discoveries in Alaska, Central Asia, Siberia, and the northern areas surrounding the North Pole, Russian explorers have made significant contributions to the exploration of the Antarctic, Arctic, and the Pacific islands, as well as deep-sea and space explorations.

The 60th parallel north is a circle of latitude that is 60 degrees north of Earth's equator. It crosses Europe, Asia, the Pacific Ocean, North America, and the Atlantic Ocean.

Although it lies approximately twice as far away from the Equator as from the North Pole, the 60th parallel is half as long as the Equator line, due to the cosine of 60 degrees being 0.5. This is where the Earth bulges halfway as much as on the Equator.

The South Pole, also known as the Geographic South Pole or Terrestrial South Pole, is the point in the Southern Hemisphere where the Earth's axis of rotation meets its surface. It is called the True South Pole to distinguish from the south magnetic pole.

The South Pole is by definition the southernmost point on the Earth, lying antipodally to the North Pole. It defines geodetic latitude 90° South, as well as the direction of true south. At the South Pole all directions point North; all lines of longitude converge there, so its longitude can be defined as any degree value. No time zone has been assigned to the South Pole, so any time can be used as the local time. Along tight latitude circles, clockwise is east and counterclockwise is west. The South Pole is at the center of the Southern Hemisphere. Situated on the continent of Antarctica, it is the site of the United States Amundsen–Scott South Pole Station, which was established in 1956 and has been permanently staffed since that year.

The Arctic (/ˈɑːr(k)tɪk/; from Ancient Greek ἄρκτος (árktos) 'bear') is the polar region of Earth that surrounds the North Pole, lying north of the Arctic Circle. The Arctic region, from the IERS Reference Meridian travelling east, consists of parts of northern Norway (Nordland, Troms, Finnmark, Svalbard and Jan Mayen), northernmost Sweden (Västerbotten, Norrbotten and Lappland), northern Finland (North Ostrobothnia, Kainuu and Lappi), Russia (Murmansk, Siberia, Nenets Okrug, Novaya Zemlya), the United States (Alaska), Canada (Yukon, Northwest Territories, Nunavut), Danish Realm (Greenland), and northern Iceland (Grímsey and Kolbeinsey), along with the Arctic Ocean and adjacent seas.

Land within the Arctic region has seasonally varying snow and ice cover, with predominantly treeless permafrost under the tundra. Arctic seas contain seasonal sea ice in many places.

Svalbard (/ˈsvɑːlbɑːr(d)/ SVAHL-bar(d), Urban East Norwegian: [ˈsvɑ̂ːɫbɑr]) — formerly Spitsbergen or Spitzbergen — is a Norwegian archipelago that lies at the convergence of the Arctic Ocean with the Atlantic Ocean. North of mainland Europe, it lies about midway between the northern coast of Norway and the North Pole. The islands of the group range from 74° to 81° north latitude, and from 10° to 35° east longitude. The largest island is Spitsbergen (37,673 km), followed in size by Nordaustlandet (14,443 km), Edgeøya (5,073 km), and Barentsøya (1,288 km). Bjørnøya or Bear Island (178 km) is the most southerly island in the territory, situated some 147 km south of Spitsbergen. Other small islands in the group include Hopen to the southeast of Edgeøya, Kongsøya and Svenskøya in the east, and Kvitøya to the northeast. The largest settlement is Longyearbyen, situated in Isfjorden on the west coast of Spitsbergen.

Whalers who sailed far north in the 17th and 18th centuries used the islands as a base; subsequently, the archipelago was abandoned. Coal mining started at the beginning of the 20th century, and several permanent communities such as Pyramiden and Barentsburg were established. The Svalbard Treaty of 1920 recognizes Norwegian sovereignty, and the Norwegian Svalbard Act of 1925 made Svalbard a full part of the Kingdom of Norway. The Svalbard Treaty established Svalbard as a free economic zone and restricts the military use of the archipelago. The Norwegian Store Norske and the Russian Arktikugol remain the only mining companies in place.

The five main latitude regions of Earth's surface comprise geographical zones, divided by the major circles of latitude. The differences between them relate to climate. They are as follows:

1. The North Frigid Zone, between the North Pole at 90° N and the Arctic Circle at 66°33′50.7″ N, covers 4.12% of Earth's surface.
2. The North Temperate Zone, between the Arctic Circle at 66°33′50.7″ N and the Tropic of Cancer at 23°26′09.3″ N, covers 25.99% of Earth's surface.
3. The Torrid Zone, between the Tropic of Cancer at 23°26′09.3″ N and the Tropic of Capricorn at 23°26′09.3″ S, covers 39.78% of Earth's surface.
4. The South Temperate Zone, between the Tropic of Capricorn at 23°26′09.3″ S and the Antarctic Circle at 66°33′50.7″ S, covers 25.99% of Earth's surface.
5. The South Frigid Zone, from the Antarctic Circle at 66°33′50.7″ S and the South Pole at 90° S, covers 4.12% of Earth's surface.

On the basis of latitudinal extent, the globe is divided into three broad heat zones.

The meridian 176° east of Greenwich is a line of longitude that extends from the North Pole across the Arctic Ocean, Asia, the Pacific Ocean, New Zealand, the Southern Ocean, and Antarctica to the South Pole.

The 176th meridian east forms a great circle with the 4th meridian west.

The Antarctic (/ænˈtɑːr(k)tɪk/, US also /æntˈɑːr(k)tɪk/; commonly /ænˈɑːrtɪk/) is the polar region of Earth that surrounds the South Pole, lying within the Antarctic Circle. It is diametrically opposite of the Arctic region around the North Pole.

The Antarctic comprises the continent of Antarctica, the Kerguelen Plateau, and other island territories located on the Antarctic Plate or south of the Antarctic Convergence. The Antarctic region includes the ice shelves, waters, and all the island territories in the Southern Ocean situated south of the Antarctic Convergence, a zone approximately 32 to 48 km (20 to 30 mi) wide and varying in latitude seasonally. The region covers some 20 percent of the Southern Hemisphere, of which 5.5 percent (14 million km) is the surface area of the Antarctica continent itself. All of the land and ice shelves south of 60°S latitude are administered under the Antarctic Treaty System.