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76-619: Sawyer Bay is an Arctic waterway in the Qikiqtaaluk Region , Nunavut , Canada. It is located in Nares Strait by eastern Ellesmere Island . Benedict Glacier fills the head of the bay. Robert Peary 's 1905-1906 exploration included this bay. This Qikiqtaaluk Region , Nunavut location article is a stub . You can help Misplaced Pages by expanding it . Arctic The Arctic ( / ˈ ɑːr k t ɪ k / or / ˈ ɑːr t ɪ k / ) (from Greek ἄρκτος, 'bear')

152-715: A Russian flag made of rust-proof titanium alloy . The flag-placing, during Arktika 2007 , generated commentary on and concern for a race for control of the Arctic's vast hydrocarbon resources. Foreign ministers and other officials representing Canada, the Kingdom of Denmark, Norway, Russia, and the United States met in Ilulissat, Greenland on 28 May 2008 at the Arctic Ocean Conference and announced

228-436: A choropleth map . In meteorology, the word isopleth is used for any type of contour line. Meteorological contour lines are based on interpolation of the point data received from weather stations and weather satellites . Weather stations are seldom exactly positioned at a contour line (when they are, this indicates a measurement precisely equal to the value of the contour). Instead, lines are drawn to best approximate

304-441: A map describing the intersection of a real or hypothetical surface with one or more horizontal planes. The configuration of these contours allows map readers to infer the relative gradient of a parameter and estimate that parameter at specific places. Contour lines may be either traced on a visible three-dimensional model of the surface , as when a photogrammetrist viewing a stereo-model plots elevation contours, or interpolated from

380-513: A ring species exists and has been described around the Arctic Circle in the form of the Larus gulls. There are copious natural resources in the Arctic (oil, gas, minerals, fresh water, fish and, if the subarctic is included, forest) to which modern technology and the economic opening up of Russia have given significant new opportunities. The interest of the tourism industry is also on

456-646: A word without a repeated letter . As late as 1944, John K. Wright still preferred isogram , but it never attained wide usage. During the early 20th century, isopleth ( πλῆθος , plethos , 'amount') was being used by 1911 in the United States, while isarithm ( ἀριθμός , arithmos , 'number') had become common in Europe. Additional alternatives, including the Greek-English hybrid isoline and isometric line ( μέτρον , metron , 'measure'), also emerged. Despite attempts to select

532-411: A constant pressure surface chart. Isohypse and isoheight are simply known as lines showing equal pressure on a map. An isotherm (from Ancient Greek θέρμη (thermē)  'heat') is a line that connects points on a map that have the same temperature . Therefore, all points through which an isotherm passes have the same or equal temperatures at the time indicated. An isotherm at 0 °C

608-417: A contour map is the difference in elevation between successive contour lines. The gradient of the function is always perpendicular to the contour lines. When the lines are close together the magnitude of the gradient is large: the variation is steep. A level set is a generalization of a contour line for functions of any number of variables. Contour lines are curved, straight or a mixture of both lines on

684-407: A curve of constant electric potential . Whether crossing an equipotential line represents ascending or descending the potential is inferred from the labels on the charges. In three dimensions, equipotential surfaces may be depicted with a two dimensional cross-section, showing equipotential lines at the intersection of the surfaces and the cross-section. The general mathematical term level set

760-431: A given location and is used in the generation of isochrone maps . An isotim shows equivalent transport costs from the source of a raw material, and an isodapane shows equivalent cost of travel time. Contour lines are also used to display non-geographic information in economics. Indifference curves (as shown at left) are used to show bundles of goods to which a person would assign equal utility. An isoquant (in

836-828: A line of constant annual variation of magnetic declination . An isoclinic line connects points of equal magnetic dip , and an aclinic line is the isoclinic line of magnetic dip zero. An isodynamic line (from δύναμις or dynamis meaning 'power') connects points with the same intensity of magnetic force. Besides ocean depth, oceanographers use contour to describe diffuse variable phenomena much as meteorologists do with atmospheric phenomena. In particular, isobathytherms are lines showing depths of water with equal temperature, isohalines show lines of equal ocean salinity, and isopycnals are surfaces of equal water density. Various geological data are rendered as contour maps in structural geology , sedimentology , stratigraphy and economic geology . Contour maps are used to show

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912-556: A number of definitions of what area is contained within the Arctic. The area can be defined as north of the Arctic Circle (about 66° 34'N), the approximate southern limit of the midnight sun and the polar night . Another definition of the Arctic, which is popular with ecologists , is the region in the Northern Hemisphere where the average temperature for the warmest month (July) is below 10 °C (50 °F);

988-426: A picture of the major thermodynamic factors in a weather system. An isobar (from Ancient Greek βάρος (baros)  'weight') is a line of equal or constant pressure on a graph, plot, or map; an isopleth or contour line of pressure. More accurately, isobars are lines drawn on a map joining places of equal average atmospheric pressure reduced to sea level for a specified period of time. In meteorology ,

1064-440: A point; this distinction has since been followed generally. An example of an isopleth is population density , which can be calculated by dividing the population of a census district by the surface area of that district. Each calculated value is presumed to be the value of the variable at the centre of the area, and isopleths can then be drawn by a process of interpolation . The idea of an isopleth map can be compared with that of

1140-489: A single standard, all of these alternatives have survived to the present. When maps with contour lines became common, the idea spread to other applications. Perhaps the latest to develop are air quality and noise pollution contour maps, which first appeared in the United States in approximately 1970, largely as a result of national legislation requiring spatial delineation of these parameters. Contour lines are often given specific names beginning with " iso- " according to

1216-421: A specific time interval, and katallobars , lines joining points of equal pressure decrease. In general, weather systems move along an axis joining high and low isallobaric centers. Isallobaric gradients are important components of the wind as they increase or decrease the geostrophic wind . An isopycnal is a line of constant density. An isoheight or isohypse is a line of constant geopotential height on

1292-461: A variety of scales, from large-scale engineering drawings and architectural plans, through topographic maps and bathymetric charts , up to continental-scale maps. "Contour line" is the most common usage in cartography , but isobath for underwater depths on bathymetric maps and isohypse for elevations are also used. In cartography, the contour interval is the elevation difference between adjacent contour lines. The contour interval should be

1368-787: A vertical section. In 1801, the chief of the French Corps of Engineers, Haxo , used contour lines at the larger scale of 1:500 on a plan of his projects for Rocca d'Anfo , now in northern Italy, under Napoleon . By around 1843, when the Ordnance Survey started to regularly record contour lines in Great Britain and Ireland , they were already in general use in European countries. Isobaths were not routinely used on nautical charts until those of Russia from 1834, and those of Britain from 1838. As different uses of

1444-503: Is a polar region located at the northernmost part of Earth. 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 ),

1520-446: Is a contour line for a variable which measures direction. In meteorology and in geomagnetics, the term isogon has specific meanings which are described below. An isocline ( κλίνειν , klinein , 'to lean or slope') is a line joining points with equal slope. In population dynamics and in geomagnetics, the terms isocline and isoclinic line have specific meanings which are described below. A curve of equidistant points

1596-519: Is a large variance in predictions of Arctic sea ice loss, with models showing near-complete to complete loss in September from 2035 to some time around 2067. Arctic life is characterized by adaptation to short growing seasons with long periods of sunlight, and cold, dark, snow-covered winter conditions. Arctic vegetation is composed of plants such as dwarf shrubs , graminoids , herbs , lichens , and mosses , which all grow relatively close to

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1672-452: Is a line joining points with constant wind speed. In meteorology, the term isogon refers to a line of constant wind direction. An isopectic line denotes equal dates of ice formation each winter, and an isotac denotes equal dates of thawing. Contours are one of several common methods used to denote elevation or altitude and depth on maps . From these contours, a sense of the general terrain can be determined. They are used at

1748-438: Is a line of equal or constant dew point . An isoneph is a line indicating equal cloud cover. An isochalaz is a line of constant frequency of hail storms, and an isobront is a line drawn through geographical points at which a given phase of thunderstorm activity occurred simultaneously. Snow cover is frequently shown as a contour-line map. An isotach (from Ancient Greek ταχύς (tachus)  'fast')

1824-522: Is a line of equal temperature beneath the Earth's surface. An isohyet or isohyetal line (from Ancient Greek ὑετός (huetos)  'rain') is a line on a map joining points of equal rainfall in a given period. A map with isohyets is called an isohyetal map . An isohume is a line of constant relative humidity , while an isodrosotherm (from Ancient Greek δρόσος (drosos)  'dew' and θέρμη (therme)  'heat')

1900-485: Is a set of points all at the same distance from a given point , line , or polyline . In this case the function whose value is being held constant along a contour line is a distance function . In 1944, John K. Wright proposed that the term isopleth be used for contour lines that depict a variable which cannot be measured at a point, but which instead must be calculated from data collected over an area, as opposed to isometric lines for variables that could be measured at

1976-520: Is a unique area among Earth's ecosystems. The cultures in the region and the Arctic indigenous peoples have adapted to its cold and extreme conditions. Life in the Arctic includes zooplankton and phytoplankton , fish and marine mammals , birds, land animals, plants and human societies. Arctic land is bordered by the subarctic . The word Arctic comes from the Greek word ἀρκτικός ( arktikos ), "near

2052-677: Is also claiming a large swath of seabed along the Lomonosov Ridge but, unlike Denmark, confined its claim to its side of the Arctic region. In August 2015, Russia made a supplementary submission for the expansion of the external borders of its continental shelf in the Arctic Ocean , asserting that the eastern part of the Lomonosov Ridge and the Mendeleyev Ridge are an extension of the Eurasian continent. In August 2016,

2128-432: Is also a concern. Because of the amplified response of the Arctic to global warming, it is often seen as a leading indicator of global warming. The melting of Greenland's ice sheet is linked to polar amplification. The Arctic region is especially vulnerable to the effects of any climate change , as has become apparent with the reduction of sea ice in recent years. Climate models predict much greater climate change in

2204-486: Is also predicted to have a large impact on tundra vegetation, causing an increase of shrubs, and having a negative impact on bryophytes and lichens. Apart from concerns regarding the detrimental effects of warming in the Arctic, some potential opportunities have gained attention. The melting of the ice is making the Northwest Passage , shipping routes through the northernmost latitudes, more navigable, raising

2280-616: Is called the freezing level . The term lignes isothermes (or lignes d'égale chaleur) was coined by the Prussian geographer and naturalist Alexander von Humboldt , who as part of his research into the geographical distribution of plants published the first map of isotherms in Paris, in 1817. According to Thomas Hankins, the Scottish engineer William Playfair 's graphical developments greatly influenced Alexander von Humbolt's invention of

2356-508: Is especially important in riparian zones. An isoflor is an isopleth contour connecting areas of comparable biological diversity. Usually, the variable is the number of species of a given genus or family that occurs in a region. Isoflor maps are thus used to show distribution patterns and trends such as centres of diversity. In economics , contour lines can be used to describe features which vary quantitatively over space. An isochrone shows lines of equivalent drive time or travel time to

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2432-403: Is found on a map dated 1584 of the river Spaarne , near Haarlem , by Dutchman Pieter Bruinsz. In 1701, Edmond Halley used such lines (isogons) on a chart of magnetic variation. The Dutch engineer Nicholas Cruquius drew the bed of the river Merwede with lines of equal depth (isobaths) at intervals of 1 fathom in 1727, and Philippe Buache used them at 10-fathom intervals on a chart of

2508-454: Is indicated on maps with isoplats . Some of the most widespread applications of environmental science contour maps involve mapping of environmental noise (where lines of equal sound pressure level are denoted isobels ), air pollution , soil contamination , thermal pollution and groundwater contamination. By contour planting and contour ploughing , the rate of water runoff and thus soil erosion can be substantially reduced; this

2584-470: Is often used to describe the full collection of points having a particular potential, especially in higher dimensional space. In the study of the Earth's magnetic field , the term isogon or isogonic line refers to a line of constant magnetic declination , the variation of magnetic north from geographic north. An agonic line is drawn through points of zero magnetic declination. An isoporic line refers to

2660-412: Is shown in all areas. Conversely, for an island which consists of a plateau surrounded by steep cliffs, it is possible to use smaller intervals as the height increases. An isopotential map is a measure of electrostatic potential in space, often depicted in two dimensions with the electrostatic charges inducing that electric potential . The term equipotential line or isopotential line refers to

2736-745: Is subject to some regulatory control through the International Code for Ships Operating in Polar Waters , adopted by the International Maritime Organization on 1 January 2017 and applies to all ships in Arctic waters over 500 tonnes. Research in the Arctic has long been a collaborative international effort, evidenced by the International Polar Year . The International Arctic Science Committee , hundreds of scientists and specialists of

2812-606: The Muttaburrasaurus of Australia. However, others claim that dinosaurs lived year-round at very high latitudes, such as near the Colville River , which is now at about 70° N but at the time (70 million years ago) was 10° further north. 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 BCE . AST consisted of several Paleo-Eskimo cultures, including

2888-692: The Arctic Council , and the Barents Euro-Arctic Council are more examples of collaborative international Arctic research. While there are several ongoing territorial claims in the Arctic , no country owns the geographic North Pole or the region of the Arctic Ocean surrounding it. The surrounding six Arctic states that border the Arctic Ocean—Canada, Kingdom of Denmark (with Greenland), Iceland, Norway, Russia, and

2964-667: The Arctic poppy ). Herbivores on the tundra include the Arctic hare , lemming , muskox , and reindeer (caribou). They are preyed on by the snowy owl , Arctic fox , grizzly bear , and Arctic wolf . The polar bear is also a predator, though it prefers to hunt for marine life from the ice. There are also many birds and marine species endemic to the colder regions. Other terrestrial animals include wolverines , moose , Dall sheep , ermines , and Arctic ground squirrels . Marine mammals include seals , walruses , and several species of cetacean — baleen whales and also narwhals , orcas , and belugas . An excellent and famous example of

3040-623: The English Channel that was prepared in 1737 and published in 1752. Such lines were used to describe a land surface (contour lines) in a map of the Duchy of Modena and Reggio by Domenico Vandelli in 1746, and they were studied theoretically by Ducarla in 1771, and Charles Hutton used them in the Schiehallion experiment . In 1791, a map of France by J. L. Dupain-Triel used contour lines at 20-metre intervals, hachures, spot-heights and

3116-627: The Ilulissat Declaration , blocking any "new comprehensive international legal regime to govern the Arctic Ocean," and pledging "the orderly settlement of any possible overlapping claims." As of 2012, the Kingdom of Denmark is claiming the continental shelf based on the Lomonosov Ridge between Greenland and over the North Pole to the northern limit of the exclusive economic zone of Russia . The Russian Federation

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3192-617: The Independence cultures and Pre-Dorset culture. 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 BCE. With the exception of the Quebec / Labrador peninsula, the Dorset culture vanished around 1500 CE. Supported by genetic testing , evidence shows that descendants of

3268-852: The UN Commission on the Limits of the Continental Shelf began to consider Russia's submission. Canada claims the Northwest Passage as part of its internal waters belonging to Canada, while the United States and most maritime nations regards it as an international strait , which means that foreign vessels have right of transit passage. Since 1937, the larger portion of the Asian-side Arctic region has been extensively explored by Soviet and Russian crewed drifting ice stations . Between 1937 and 1991, 88 international polar crews established and occupied scientific settlements on

3344-562: The United Nations Conference on Sustainable Development , on 21 June 2012, proposed protecting the Arctic, similar to the Antarctic Treaty System . The initial focus of the campaign will be a UN resolution creating a global sanctuary around the pole, and a ban on oil drilling and unsustainable fishing in the Arctic. The Arctic has climate change rates that are amongst the highest in the world. Due to

3420-514: The barometric pressures shown are reduced to sea level , not the surface pressures at the map locations. The distribution of isobars is closely related to the magnitude and direction of the wind field, and can be used to predict future weather patterns. Isobars are commonly used in television weather reporting. Isallobars are lines joining points of equal pressure change during a specific time interval. These can be divided into anallobars , lines joining points of equal pressure increase during

3496-430: The drift ice and were carried thousands of kilometres by the ice flow. The Arctic is comparatively clean, although there are certain ecologically difficult localized pollution problems that present a serious threat to people's health living around these pollution sources. Due to the prevailing worldwide sea and air currents, the Arctic area is the fallout region for long-range transport pollutants , and in some places

3572-424: The permafrost thaws. The melting of Greenland's ice sheet is linked to polar amplification . Due to the poleward migration of the planet's isotherms (about 56 km (35 mi) per decade during the past 30 years as a consequence of global warming), the Arctic region (as defined by tree line and temperature) is currently shrinking. Perhaps the most alarming result of this is Arctic sea ice shrinkage. There

3648-685: The Arctic than the global average, resulting in significant international attention to the region. In particular, there are concerns that Arctic shrinkage, a consequence of melting glaciers and other ice in Greenland, could soon contribute to a substantial rise in sea levels worldwide. The current Arctic warming is leading to ancient carbon being released from thawing permafrost , leading to methane and carbon dioxide production by micro-organisms. Release of methane and carbon dioxide stored in permafrost could cause abrupt and severe global warming, as they are potent greenhouse gases . Climate change

3724-473: The Bear, northern" and from the word ἄρκτος ( arktos ), meaning bear. The name refers either to the constellation known as Ursa Major , the "Great Bear", which is prominent in the northern portion of the celestial sphere , or to the constellation Ursa Minor , the "Little Bear", which contains the celestial north pole (currently very near Polaris , the current north Pole Star, or North Star). There are

3800-606: The Dorset culture, known as the Sadlermiut , survived in Aivilik, Southampton and Coats Islands , until the beginning of the 20th century. The Dorset / Thule culture transition dates around the ninth–10th centuries CE. 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 their ways with

3876-525: The Dorset people in "an example of prehistoric genocide." By 1300 CE, the Inuit , present-day Arctic inhabitants and descendants of Thule culture, had settled in west Greenland, and moved into east Greenland over the following century ( Inughuit , Kalaallit and Tunumiit are modern Greenlandic Inuit groups descended from Thule). Over time, the Inuit have migrated throughout the Arctic regions of Eastern Russia,

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3952-527: The North , and Saami Council ). The council operates on consensus basis, mostly dealing with environmental treaties and not addressing boundary or resource disputes. Though Arctic policy priorities differ , every Arctic nation is concerned about sovereignty/defense, resource development, shipping routes, and environmental protection. Much work remains on regulatory agreements regarding shipping, tourism, and resource development in Arctic waters. Arctic shipping

4028-422: 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. The Arctic region

4104-758: The United States, Canada, and Greenland. Other Circumpolar North indigenous peoples include the Chukchi , Evenks , Iñupiat , Khanty , Koryaks , Nenets , Sámi , Yukaghir , Gwichʼin , and Yupik . The eight Arctic nations (Canada, Kingdom of Denmark [Greenland & The Faroe Islands], Finland, Iceland, Norway, Sweden, Russia, and US) are all members of the Arctic Council , as are organizations representing six indigenous populations (The Aleut International Association , Arctic Athabaskan Council , Gwich'in Council International , Inuit Circumpolar Council , Russian Association of Indigenous Peoples of

4180-679: The United States—are limited to a 200 nautical miles (370 km; 230 mi) exclusive economic zone (EEZ) off their coasts. Two Arctic states (Finland and Sweden) do not have direct access to the Arctic Ocean. Upon ratification of the United Nations Convention on the Law of the Sea , a country has ten years to make claims to an extended continental shelf beyond its 200 nautical mile zone. Due to this, Norway (which ratified

4256-452: The below ground surface of geologic strata , fault surfaces (especially low angle thrust faults ) and unconformities . Isopach maps use isopachs (lines of equal thickness) to illustrate variations in thickness of geologic units. In discussing pollution, density maps can be very useful in indicating sources and areas of greatest contamination. Contour maps are especially useful for diffuse forms or scales of pollution. Acid precipitation

4332-504: The coldest recorded temperature is approximately −68 °C (−90 °F). Coastal Arctic climates are moderated by oceanic influences, having generally warmer temperatures and heavier snowfalls than the colder and drier interior areas. The Arctic is affected by current global warming , leading to climate change in the Arctic , including Arctic sea ice decline , diminished ice in the Greenland ice sheet , and Arctic methane emissions as

4408-399: The concentrations exceed the levels of densely populated urban areas. An example of this is the phenomenon of Arctic haze , which is commonly blamed on long-range pollutants. Another example is with the bioaccumulation of PCB's ( polychlorinated biphenyls ) in Arctic wildlife and people. There have been many proposals to preserve the Arctic over the years. Most recently a group of stars at

4484-413: The convention in 1996), Russia (ratified in 1997), Canada (ratified in 2003) and the Kingdom of Denmark (ratified in 2004) launched projects to establish claims that certain sectors of the Arctic seabed should belong to their territories. On 2 August 2007, two Russian bathyscaphes , MIR-1 and MIR-2 , for the first time in history descended to the Arctic seabed beneath the North Pole and placed there

4560-428: The estimated surface elevations , as when a computer program threads contours through a network of observation points of area centroids. In the latter case, the method of interpolation affects the reliability of individual isolines and their portrayal of slope , pits and peaks. The idea of lines that join points of equal value was rediscovered several times. The oldest known isobath (contour line of constant depth)

4636-429: The ground, forming tundra . An example of a dwarf shrub is the bearberry . As one moves northward, the amount of warmth available for plant growth decreases considerably. In the northernmost areas, plants are at their metabolic limits, and small differences in the total amount of summer warmth make large differences in the amount of energy available for maintenance, growth and reproduction. Colder summer temperatures cause

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4712-456: The image at right) is a curve of equal production quantity for alternative combinations of input usages , and an isocost curve (also in the image at right) shows alternative usages having equal production costs. In political science an analogous method is used in understanding coalitions (for example the diagram in Laver and Shepsle's work ). In population dynamics , an isocline shows

4788-424: The increase. The Arctic contains some of the last and most extensive continuous wilderness areas in the world, and its significance in preserving biodiversity and genotypes is considerable. The increasing presence of humans fragments vital habitats. The Arctic is particularly susceptible to the abrasion of groundcover and to the disturbance of the rare breeding grounds of the animals that are characteristic to

4864-429: The isotherm. Humbolt later used his visualizations and analyses to contradict theories by Kant and other Enlightenment thinkers that non-Europeans were inferior due to their climate. An isocheim is a line of equal mean winter temperature, and an isothere is a line of equal mean summer temperature. An isohel ( ἥλιος , helios , 'Sun') is a line of equal or constant solar radiation . An isogeotherm

4940-442: The locations of exact values, based on the scattered information points available. Meteorological contour maps may present collected data such as actual air pressure at a given time, or generalized data such as average pressure over a period of time, or forecast data such as predicted air pressure at some point in the future. Thermodynamic diagrams use multiple overlapping contour sets (including isobars and isotherms) to present

5016-406: The major impacts to the region from climate change the near climate future of the region will be extremely different under all scenarios of warming. The effects of climate change in the Arctic include rising temperatures, loss of sea ice , and melting of the Greenland ice sheet . Potential methane release from the region, especially through the thawing of permafrost and methane clathrates ,

5092-427: The map key. Usually contour intervals are consistent throughout a map, but there are exceptions. Sometimes intermediate contours are present in flatter areas; these can be dashed or dotted lines at half the noted contour interval. When contours are used with hypsometric tints on a small-scale map that includes mountains and flatter low-lying areas, it is common to have smaller intervals at lower elevations so that detail

5168-482: The nature of the variable being mapped, although in many usages the phrase "contour line" is most commonly used. Specific names are most common in meteorology, where multiple maps with different variables may be viewed simultaneously. The prefix "' iso- " can be replaced with " isallo- " to specify a contour line connecting points where a variable changes at the same rate during a given time period. An isogon (from Ancient Greek γωνία (gonia)  'angle')

5244-464: The northernmost tree line roughly follows the isotherm at the boundary of this region. The climate of the Arctic region is characterized by cold winters and cool summers. Its precipitation mostly comes in the form of snow and is low, with most of the area receiving less than 50 cm (20 in). High winds often stir up snow, creating the illusion of continuous snowfall. Average winter temperatures can go as low as −40 °C (−40 °F), and

5320-671: The possibility that the Arctic region will become a prime trade route . One harbinger of the opening navigability of the Arctic took place in the summer of 2016 when the Crystal Serenity successfully navigated the Northwest Passage, a first for a large cruise ship. In addition, it is believed that the Arctic seabed may contain substantial oil fields which may become accessible if the ice covering them melts. These factors have led to recent international debates as to which nations can claim sovereignty or ownership over

5396-523: The predecessor culture. The evidence suggested that Inuit descend from the Birnirk of Siberia, who through the Thule culture expanded into northern Canada and Greenland, where they genetically and culturally completely replaced the Indigenous Dorset people some time after 1300 CE. The question of why the Dorset disappeared so completely has led some to suggest that Thule invaders wiped out

5472-725: The region. The Arctic also holds 1/5 of the Earth's water supply. During the Cretaceous time period , the Arctic still had seasonal snows, though only a light dusting and not enough to permanently hinder plant growth. Animals such as the Chasmosaurus , Hypacrosaurus , Troodon , and Edmontosaurus may have all migrated north to take advantage of the summer growing season, and migrated south to warmer climes when winter came. A similar situation may also have been found amongst dinosaurs that lived in Antarctic regions, such as

5548-407: The same over a single map. When calculated as a ratio against the map scale, a sense of the hilliness of the terrain can be derived. There are several rules to note when interpreting terrain contour lines: Of course, to determine differences in elevation between two points, the contour interval, or distance in altitude between two adjacent contour lines, must be known, and this is normally stated in

5624-432: The size, abundance, productivity and variety of plants to decrease. Trees cannot grow in the Arctic, but in its warmest parts, shrubs are common and can reach 2 m (6 ft 7 in) in height; sedges , mosses and lichens can form thick layers. In the coldest parts of the Arctic, much of the ground is bare; non-vascular plants such as lichens and mosses predominate, along with a few scattered grasses and forbs (like

5700-440: The technique were invented independently, cartographers began to recognize a common theme, and debated what to call these "lines of equal value" generally. The word isogram (from Ancient Greek ἴσος (isos)  'equal' and γράμμα (gramma)  'writing, drawing') was proposed by Francis Galton in 1889 for lines indicating equality of some physical condition or quantity, though isogram can also refer to

5776-440: The waters of the Arctic. Contour line#Temperature and related subjects In cartography , a contour line (often just called a "contour") joins points of equal elevation (height) above a given level, such as mean sea level . A contour map is a map illustrated with contour lines, for example a topographic map , which thus shows valleys and hills, and the steepness or gentleness of slopes. The contour interval of

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