|
Circumpolar
Circumpolar may refer to: * Antarctic region ** Antarctic Circle ** the Antarctic Circumpolar Current ** Subantarctic ** List of Antarctic and subantarctic islands ** Antarctic Convergence ** Antarctic Circumpolar Wave ** Antarctic Ocean * Arctic region ** Arctic Circle ** Subarctic ** Circumpolar peoples ** Arctic Cooperation and Politics ** Arctic Ocean ** List of islands in the Arctic Ocean * Circumpolar constellation, a constellation that never rises or sets from the perspective of a given latitude on Earth ** Circumpolar star, a star that never rises or sets from the perspective of a given latitude on Earth * Polar front in meteorology * circumpolar navigation, a global circumnavigation which traverses both poles See also * Circumpolar distribution *Antipodes In geography, the antipode () of any spot on Earth is the point on Earth's surface diametrically opposite to it. A pair of points ''antipodal'' () to each other are situated such that a straight line connecting th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antarctic Circumpolar Current
The Antarctic Circumpolar Current (ACC) is an ocean current that flows clockwise (as seen from the South Pole) from west to east around Antarctica. An alternative name for the ACC is the West Wind Drift. The ACC is the dominant circulation feature of the Southern Ocean and has a mean transport estimated at 100–150 Sverdrups (Sv, million m3/s), or possibly even higher, making it the largest ocean current. The current is circumpolar due to the lack of any landmass connecting with Antarctica and this keeps warm ocean waters away from Antarctica, enabling that continent to maintain its huge ice sheet. Associated with the Circumpolar Current is the Antarctic Convergence, where the cold Antarctic waters meet the warmer waters of the subantarctic, creating a zone of upwelling nutrients. These nurture high levels of phytoplankton with associated copepods and krill, and resultant foodchains supporting fish, whales, seals, penguins, albatrosses, and a wealth of other species. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antarctic Ocean
The Southern Ocean, also known as the Antarctic Ocean, comprises the southernmost waters of the World Ocean, generally taken to be south of 60° S latitude and encircling Antarctica. With a size of , it is regarded as the second-smallest of the five principal oceanic divisions: smaller than the Pacific, Atlantic Ocean, Atlantic, and Indian Ocean, Indian oceans but larger than the Arctic Ocean. Over the past 30 years, the Southern Ocean has been subject to rapid climate change, which has led to changes in the marine ecosystem. By way of his voyages in the 1770s, James Cook proved that waters encompassed the southern latitudes of the globe. Since then, geographers have disagreed on the Southern Ocean's northern boundary or even existence, considering the waters as various parts of the Pacific, Atlantic, and Indian oceans, instead. However, according to Commodore John Leech of the International Hydrographic Organization (IHO), recent oceanographic research has discovered ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circumpolar Star
A circumpolar star is a star that, as viewed from a given latitude on Earth, never sets below the horizon due to its apparent proximity to one of the celestial poles. Circumpolar stars are therefore visible from said location toward the nearest pole for the entire night on every night of the year (and would be continuously visible throughout the day too, were they not overwhelmed by the Sun's glare). Others are called ''seasonal'' stars. All circumpolar stars lie within a circumpolar circle whose size is determined by the observer's latitude. Specifically, the angular measure of the radius of this circle equals the observer's latitude. The closer the observer is to the North or South Pole, the larger the circumpolar circle is. Before the definition of the Arctic was formalized as the region north of the Arctic Circle which experiences the Midnight sun, it more broadly meant those places where the 'bear' constellations (Ursa Major, the Great Bear, and Ursa Minor, the Little Bear ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circumpolar Constellation
A circumpolar star is a star that, as viewed from a given latitude on Earth, never sets below the horizon due to its apparent proximity to one of the celestial poles. Circumpolar stars are therefore visible from said location toward the nearest pole for the entire night on every night of the year (and would be continuously visible throughout the day too, were they not overwhelmed by the Sun's glare). Others are called ''seasonal'' stars. All circumpolar stars lie within a circumpolar circle whose size is determined by the observer's latitude. Specifically, the angular measure of the radius of this circle equals the observer's latitude. The closer the observer is to the North or South Pole, the larger the circumpolar circle is. Before the definition of the Arctic was formalized as the region north of the Arctic Circle which experiences the Midnight sun, it more broadly meant those places where the 'bear' constellations (Ursa Major, the Great Bear, and Ursa Minor, the Little Bear) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circumpolar Peoples
Circumpolar peoples and Arctic peoples are umbrella terms for the various Indigenous peoples of the Arctic. Prehistory The earliest inhabitants of North America's central and eastern Arctic are referred to as the Arctic small tool tradition (AST) and existed c. 2500 BC. AST consisted of several Paleo-Eskimo cultures, including the Independence cultures and Pre-Dorset culture.Gibbon, pp. 28–31 The Dorset culture (Inuktitut: ''Tuniit'' or ''Tunit'') refers to the next inhabitants of central and eastern Arctic. The Dorset culture evolved because of technological and economic changes during the period of 1050–550 BC. With the exception of the Quebec/Labrador peninsula, the Dorset culture vanished around 1500 AD. Dorset/Thule culture transition dates around the 9th–10th centuries. Scientists theorize that there may have been cross-contact of the two cultures with sharing of technology, such as fashioning harpoon heads, or the Thule may have found Dorset remnants and adapted the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antarctic Circumpolar Wave
The Antarctic Circumpolar Wave (ACW) is a coupled ocean/ atmosphere wave that circles the Southern Ocean in approximately eight years at . Since it is a wave-2 phenomenon (there are two ridges and two troughs in a latitude circle) at each fixed point in space a signal with a period of four years is seen. The wave moves eastward with the prevailing currents. History of the concept Although the "wave" is seen in temperature, atmospheric pressure, sea ice and ocean height, the variations are hard to see in the raw data and need to be filtered to become apparent. Because the reliable record for the Southern Ocean is short (since the early 1980s) and signal processing is needed to reveal its existence, some climatologists doubt the existence of the wave. Others accept its existence but say that it varies in strength over decades. The wave was discovered simultaneously by and . Since then, ideas about the wave structure and maintenance mechanisms have changed and grown: by some a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subantarctic
The sub-Antarctic zone is a region in the Southern Hemisphere, located immediately north of the Antarctic region. This translates roughly to a latitude of between 46° and 60° south of the Equator. The subantarctic region includes many islands in the southern parts of the Atlantic, Indian, and Pacific oceans, especially those situated north of the Antarctic Convergence. Sub-Antarctic glaciers are, by definition, located on islands within the sub-Antarctic region. All glaciers located on the continent of Antarctica are by definition considered to be Antarctic glaciers. Geography The sub-Antarctic region comprises two geographic zones and three distinct fronts. The northernmost boundary of the subantarctic region is the rather ill-defined Subtropical Front (STF), also referred to as the Subtropical Convergence. To the south of the STF is a geographic zone, the Subantarctic Zone (SAZ). South of the SAZ is the Subantarctic Front (SAF). South of the SAF is another marine zone, cal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circumpolar Distribution
A circumpolar distribution is any range of a taxon that occurs over a wide range of longitudes but only at high latitudes; such a range therefore extends all the way around either the North Pole or the South Pole. Taxa that are also found in isolated high-mountain environments further from the poles are said to have arctic–alpine distributions. Animals with circumpolar distributions include the reindeer, polar bear, Arctic fox, snowy owl, snow bunting, king eider, brent goose and long-tailed skua in the north, and the Weddell seal and Adélie penguin in the south. Plants with northern circumpolar distributions include ''Eutrema edwardsii'' (syn. ''Draba laevigata''), ''Saxifraga oppositifolia'', ''Persicaria vivipara'' and ''Honckenya peploides ''Honckenya peploides'', the sea sandwort (UK) or seaside sandplant (Canada), is the only species in the genus ''Honckenya'' of the plant family Caryophyllaceae. Other common names include sea chickweed, sea pimpernal, sea-beach sandwor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arctic Circle
The Arctic Circle is one of the two polar circles, and the most northerly of the five major circles of latitude as shown on maps of Earth. Its southern equivalent is the Antarctic Circle. The Arctic Circle marks the southernmost latitude at which, on the December solstice, the shortest day of the year in the northern hemisphere, the sun will not rise all day, and on the June solstice, the longest day of the year in the northern hemisphere, the sun will not set. These phenomena are referred to as polar night and midnight sun respectively, and the further north one progresses, the more pronounced these effects become. For example, in the Russian port city of Murmansk, three degrees above the Arctic Circle, the sun does not rise for 40 successive days in midwinter. The position of the Arctic Circle is not fixed and currently runs north of the Equator. Its latitude depends on the Earth's axial tilt, which fluctuates within a margin of more than 2° over a 41,000-year period, o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arctic Cooperation And Politics
Arctic cooperation and politics are partially coordinated via the Arctic Council, composed of the eight Arctic nations: the United States, Canada, Iceland, Norway, Sweden, Finland, Russia, and Denmark with Greenland and the Faroe Islands. The dominant governmental power in Arctic policy resides within the executive offices, legislative bodies, and implementing agencies of the eight Arctic nations, and to a lesser extent other nations, such as United Kingdom, Germany, European Union and China. NGOs and academia play a large part in Arctic policy. Also important are intergovernmental bodies such as the United Nations (especially as relates to the Law of the Sea Treaty) and NATO. Though Arctic policy priorities differ, every Arctic nation is concerned about sovereignty and defense, resource development, shipping routes, and environmental protection. Though several boundary and resource disputes in the Arctic remain unsolved, there is remarkable conformity of stated policy directives a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antarctic Convergence
The Antarctic Convergence or Antarctic Polar Front is a marine belt encircling Antarctica, varying in latitude seasonally, where cold, northward-flowing Antarctic waters meet the relatively warmer waters of the sub-Antarctic. Antarctic waters predominantly sink beneath the warmer subantarctic waters, while associated zones of mixing and upwelling create a zone very high in marine productivity, especially for Antarctic krill. This line, like the arctic tree line, is a natural boundary rather than an artificial one, such as the borders of nations and time zones. It not only separates two hydrological regions, but also separates areas of distinctive marine life and climates. The Arctic has no similar boundary because of the large bodies of land contiguous with the northern polar region. History The Antarctic Convergence was first crossed by Anthony de la Roché in 1675, and described by Edmond Halley in 1700. Location The Antarctic Convergence is a zone approximately wide, v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subarctic
The subarctic zone is a region in the Northern Hemisphere immediately south of the true Arctic, north of humid continental regions and covering much of Alaska, Canada, Iceland, the north of Scandinavia, Siberia, and the Cairngorms. Generally, subarctic regions fall between 50°N and 70°N latitude, depending on local climates. Precipitation is usually low, and vegetation is characteristic of the taiga. Daylight at these latitudes is quite extreme between summer and winter due to its high latitude. Near the summer solstice for instance, subarctic regions can experience an all-night period of either civil, nautical, or astronomical twilight (or in the northern reaches full daylight), but without true night, since the sun never dips more than 18 degrees below the horizon. Noctilucent clouds are best observed within this range of latitude. Climate and soils Subarctic temperatures are above for at least one and at most three months of the year. Precipitation tends to be low du ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
