Circumpolar

Last updated March 20, 2019

Circumpolar may refer to:

Antarctic region
The Antarctic Convergence or Antarctic Polar Front is a curve continuously encircling Antarctica, varying in latitude seasonally, where cold, northward-flowing Antarctic waters meet the relatively warmer waters of the subantarctic. Antarctic waters predominantly sink beneath 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 like a line of latitude. It not only separates two hydrological regions, but also separates areas of distinctive marine life associations and of different climates. There is no Arctic equivalent, due to the amount of land contiguous with the northern polar region.
The Antarctic Circumpolar Wave (ACW) is a coupled ocean/atmosphere wave that circles the Southern Ocean in approximately eight years at 6–8 cm/s (2.4–3.1 in/s). Since it is a wave-2 phenomenon at each fixed point in space a signal with a period of four years is seen. The wave moves eastward with the prevailing currents.
Arctic region
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. It marks the northernmost point at which the centre of the noon sun is just visible on the December solstice and the southernmost point at which the centre of the midnight sun is just visible on the June solstice. The region north of this circle is known as the Arctic, and the zone just to the south is called the Northern Temperate Zone.
The subarctic is a region in the Northern Hemisphere immediately south of the true Arctic and covering much of Alaska, Canada, Iceland, the north of Scandinavia, Siberia, the Shetland Islands, and the Cairngorms. Generally, subarctic regions fall between 50°N and 70°N latitude, depending on local climates. Precipitation is low, and vegetation is characteristic of the taiga.
Circumpolar peoples and Arctic peoples are umbrella terms for the various indigenous peoples of the Arctic.
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
A circumpolar star is a star, as viewed from a given latitude on Earth, that 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.
Polar front in meteorology
circumpolar navigation, a global circumnavigation which traverses both poles

The Antarctic Circle is the most southerly of the five major circles of latitude that mark maps of the Earth. The region south of this circle is known as the Antarctic, and the zone immediately to the north is called the Southern Temperate Zone. South of the Antarctic Circle, the sun is above the horizon for 24 continuous hours at least once per year and the centre of the sun is below the horizon for 24 continuous hours at least once per year ; this is also true within the equivalent polar circle in the Northern Hemisphere, the Arctic Circle.

The Antarctic Circumpolar Current (ACC) is an ocean current that flows clockwise 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, 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.

The Subantarctic 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 Indian Ocean, Atlantic Ocean and Pacific Ocean, especially those situated north of the Antarctic Convergence. Subantarctic glaciers are, by definition, located on islands within the subantarctic region. All glaciers located on the continent of Antarctica are by definition considered to be Antarctic glaciers.

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Declination Astronomical coordinate analogous to latitude

In astronomy, declination is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system, the other being hour angle. Declination's angle is measured north or south of the celestial equator, along the hour circle passing through the point in question.

The Tropic of Cancer, which is also referred to as the Northern Tropic, is the most northerly circle of latitude on Earth at which the Sun can be directly overhead. This occurs on the June solstice, when the Northern Hemisphere is tilted toward the Sun to its maximum extent. It is currently 23°26′12.5″ (or 23.4368°) north of the Equator.

A circle of latitude on Earth is an abstract east–west circle connecting all locations around Earth at a given latitude.

The heliacal rising or star rise of a star occurs annually when it briefly becomes visible above the eastern horizon at dawn just before sunrise, after a period of less than a year when it had not been visible. Historically, the most important such rising is that of Sirius, which was an important feature of the Egyptian calendar and astronomical development. The rising of the Pleiades heralded the start of the Ancient Greek sailing season, using celestial navigation.

In observational astronomy, the culmination of a celestial object or constellation is either of two moments when it reaches the observer's meridian on the celestial sphere, on which it appears to move along a circular path over the course of a day, due to Earth's rotation.

Physical oceanography is the study of physical conditions and physical processes within the ocean, especially the motions and physical properties of ocean waters.

The polar regions, also called the frigid zones, of Earth are the regions of the planet that surround its geographical poles, lying within the polar circles. These high latitudes are dominated by Earth's polar ice caps: the northern resting on the Arctic Ocean and the southern on the continent of Antarctica.

Polar ecology is the relationship between plants and animals in a polar environment. Polar environments are in the Arctic and Antarctic regions. Arctic regions are in the Northern Hemisphere, and it contains land and the islands that surrounds it. Antarctica is in the Southern Hemisphere and it also contains the land mass, surrounding islands and the ocean. Polar regions also contain the subantarctic and subarctic zone which separate the polar regions from the temperate regions. Antarctica and the Arctic lie in the polar circles. The polar circles are not visible on the earth but it is shown on maps to be the areas that receives less sunlight due to less radiation. These areas either receive sunlight or shade 24 hours a day because of the earth's tilt. Plants and animals in the polar regions are able to withstand living in harsh weather conditions but are facing environmental threats that limit their survival.

In astronomy, a circumpolar constellation is a constellation that never sets below the horizon, as viewed from a location on Earth. Due to Earth's rotation and axial tilt with respect to the Sun, the stars and constellations can be divided into two categories. Those stars and constellations that never rise or set are called circumpolar. The rest are divided into seasonal stars and constellations.

On Earth, daytime is roughly the period of the day during which any given point in the world experiences natural illumination from especially direct sunlight. Daytime occurs when the Sun appears above the local horizon, that is, anywhere on the globe's hemisphere facing the Sun. During daytime, an observer sees indirect sunlight while in the shade, which includes cloud cover. 'Day' is sometimes used instead of 'daytime', in this case 'day' will mean 'the period of light between dawn and nightfall; the interval from sunrise to sunset', which is synonymous with daytime. However in this context, in order to be clear "daytime" should be used distinguish it from "day" which typically refers to a 24-hour period.

Subantarctic mode water (SAMW) is an important water mass in the Earth's oceans. It is formed near the Subantarctic Front on the northern flank of the Antarctic Circumpolar Current. The surface density of Subantarctic Mode Water ranges between about 1026.0 and 1027.0 kg/m³ and the core of this water mass is often identified as a region of particularly low stratification.

The Antarctic Floristic Kingdom, also the Holantarctic Kingdom, is a floristic kingdom. It includes most areas of the world south of 40°S latitude. It was first identified by botanist Ronald Good, and later by Armen Takhtajan. The Antarctic Floristic Kingdom is a classification in phytogeography, different from the Antarctic ecozone classification in biogeography, and from Antarctic flora genera/species classifications in botany.

Southern Ocean The ocean around Antarctica

The Southern Ocean, also known as the Antarctic Ocean or the Austral Ocean, and the "Southern Icy Ocean".</ref> comprises the southernmost waters of the World Ocean, generally taken to be south of 60° S latitude and encircling Antarctica. As such, it is regarded as the fourth largest of the five principal oceanic divisions: smaller than the Pacific, Atlantic, and Indian Oceans but larger than the Arctic Ocean. This ocean zone is where cold, northward flowing waters from the Antarctic mix with warmer subantarctic waters.

Circumpolar

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