The geographic region known as the Arctic consists of the Arctic Ocean and its peripheral coastal margins generally poleward of the Arctic Circle at 66*33' North Latitude (Ref 1).
The definition of the Arctic may be considered as a combination of the following factors: 1. Year round cold temperatures with the warmest month, usually July, having a mean temperature of 50*F (10*C); 2. Without trees, that is, north of the tree limit (the so-called timberline); and 3. Vegetation either completely absent, such as in the Greenland Ice Sheet, or in tundra which consists largely of lichens, mosses, sedges, grasses and low shrubs (Ref 2).
The cold temperatures of the Arctic are due primarily to the reduced amount of solar radiation resulting from its polar location (oblique rays of the sun deliver less radiation) and its severe seasonal alteration which results in amost total loss of solar radiation during one-half of the year (a function of the earth's tilt of its axis 23*27' from the perpendicular to the plane of the earth's orbit around the sun).
The Arctic boundary (Ref 3) is shifted north in the northeastern Atlantic Ocean due to the enormous amount of heat carried by the North Atlantic Drift, so much so that the northernmost part of Norway is ice-free year round and the Lofoten Islands experience the greatest anomaly of temperature for its latitudinal location. Similarly, the Arctic boundary is shifted south along the northwestern Atlantic as currents bring cold water, to include icebergs, south to lower latitudes. Other southward extensions of the Arctic are found in Hudson Bay and the Bering Sea where outpourings of cold Arctic Ocean waters reduce overall surface and subsurface temperatures. Surface currents in the Arctic Ocean display a clockwise rotation (Ref 4) while the North Atlantic Drift, a continuation of the Gulf Stream, contributes a most important warm current from the south. The prevailing westerlies carry the saturated air over the Norwegian landmass and provide the snow for continued existence of the snow fields and mountain glaciers inland (Ref 5).
The predominant vegetation is tundra (Ref 6) that is characterized by low shrubs, primitive lichens and mosses, grasses and the absence of coniferous forests. The gradations between the tundra and the taiga, the so-called forest-tundra zone, are depicted on the referenced map of the Kola Peninsula/White Sea area (Ref 7).
The low annual temperatures (Ref 8) produce thin infertile soils which in most areas are underlain by a frozen stratum of permafrost. This impermeable layer, 6-24 inches below the surface, causes summer meltwaters to remain unabsorbed and results in the development of extensive wetland areas.
The Subarctic, located to the south of the arctic margins, is an area of coniferous forests often referred to as the taiga or boreal forests (Ref 9).
It should be noted that the timberline or the approximate boundary between the Arctic and Subarctic is usually a zone of transition that may be 50 to 100 miles wide. The size of the coniferous trees gradually become more stunted as the Arctic region is approached.
The arctic climate of extended cold temperatures results in rather low amounts of precipitation because cold, dense air holds little moisture and the term polar desert is an apt phrase; however, little evaporation and high winds means that the so-called high arctic (where temperatures on average do not rise above freezing) displays much drifting snow with the resultant appearance of heavy snowfall. On the circumpolar margins where pack ice disappears in the summer and the terrestrial margins of the continents, which warm up in the high-sun periods, together will produce more precipitation permitting the growth of tundra and marine organisms.
Glaciers develop in snowfields that accumulate more snow than is lost in melting (Ref 10). The Subarctic and more temperate climates are better suited for mountain glacier production as the first requirement is adequate snowfall. The upland locations (3.3*F is lost for each 1,000ft increase in altitude) supply the cooler environments and gravity starts the ice moving downhill.
Fiords, or fjords, are long, narrow, steep-walled, U-shaped valleys that terminate in coastal inlets that have been typically gauged out by a glacier and subsequently filled with sea water. Inasmuch as the glacier is heavy, even though buoyed somewhat by sea water, it typically carves out a deep bottom to the fiord. Sea levels have been periodically lower in the past and glacial action has long been effective below the current sea level stage. In some instances, the furthest gauging of the glacier has left underwater morainic material that serves as a shallower threshold to the inlet and provides less depths than further inland. Tidewater glaciers, those that still come down to sea level, tend to produce berger bits and icebergs as deterioration of the leading edge permits calving off of ice into adjacent waters. Where glaciers have receded from sea level, such as in Norway, their effect is seen as melt water usually as waterfalls appearing from hanging valleys. |
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