Some North Polar Geography

by John M. MacFarlane 2016

The Arctic Circle It is the latitude at which the sun does not set for one day at mid-summer and does not rise for one day in mid-winter. The latitude varies from year to year but is approximately 66 degrees 33 minutes from the equator. On June 20 or 21, the summer solstice occurs and the sun does not set at the Arctic Circle. Due to refraction of the sunlight it appears not to set for four days. At Barrow AK the sun does not set from May 10 to August 2. At the winter solstice on December 21 or 22 the sun does not rise for one day at the Arctic Circle. At Barrow AK it does not rise for 67 days.

The North Magnetic Pole It is located between Greenland and the islands of the Canadian Arctic archipelago. The Pole itself migrates, constantly and daily, it causes a continuing error in charts and other navigation methods which depend upon compass bearings. It also migrates over a longer time period moving westward across the Arctic Islands. It was discovered in 1831 by James Clark Ross. Since then it has drifted more than 700km. It is thought that the drift is caused by the core of the electromagnetic field of the earth. The pole also wobbles, traveling around a closed path every day, roughly elliptically in shape up to 100km across. This is in response to the electromagnetic effects of electrical currents in the upper atmosphere caused by electrified particles flowing from the sun. Magnetic storms also create erratic behavior in magnetic compasses in the region. There are several severe anomaly areas in the north which behave like secondary Magnetic Poles. Whether they are actually secondary poles or simply a reflection of the way the materials in the earth’s crust are causing magnetic fields to behave is uncertain. The earth's magnetism is based on electric currents set up by movement of the molten core. The magnetic field is similar in shape to that of a flexible slightly mobile axis of rotation of 15 degrees. The two poles are not quite antipodal as though the axis of the magnet was slightly bent. It was first visited by Ross in 1831. Observers know they are there when a dip needle points vertically into the ground. Navigators in the high Arctic prefer to use sun navigation or a gyroscopic compass. The magnetic dip is 90° where a suspended needle, able to point in any direction points straight down. A compass is unreliable at high latitudes. It only indicates true north when the observer is in line with the true north pole and the magnetic pole. As the magnetic pole is approached the compass needle begins to dip down. until a horizontal force is too weak to overcome the friction in the bearings, so the needle becomes sluggish. The geomagnetic poles are located at either end of a line going through the centre of the earth. The line joining them misses the exact centre of the earth, the reason not being known.

The North Pole The geographical "top of the world", 90° north latitude, the point where all meridians of longitude intersect. The northernmost point on the globe. all directions are south from the North Pole. It is the northern end of the earth's axis. The region there receives six months of sunlight and six months of darkness. Along with the Northwest Passage the quest for the North Pole took on almost religious overtones.

The 60th Parallel orms the administrative southern boundary of Canada’s northern territories with the provinces this also tends to be the accepted demarcation of the "north". The Arctic appears to be considered as the area north of the tree line.

The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is subject to the caveats explained below, defined as the point in the northern hemisphere where the Earth's axis of rotation meets the Earth’s surface. It should not be confused with the North Magnetic Pole. The North Pole is the northernmost point on Earth, lying diametrically opposite the South Pole. It defines geodetic latitude 90° North, as well as the direction of True North. At the North Pole all directions point south; all lines of longitude converge there, so its longitude can be defined as any degree value.

While the South Pole lies on a continental land mass, the North Pole is located in the middle of the Arctic Ocean amid waters that are almost permanently covered with constantly shifting sea ice. This makes it impractical to construct a permanent station at the North Pole (unlike the South Pole). However, the Soviet Union, and later Russia, have constructed a number of manned drifting stations, some of which have passed over or very close to the Pole. In recent years, a number of studies have predicted that the North Pole may become seasonally ice-free due to Arctic shrinkage, with timescales varying from a few years to fifty years or more.

The sea depth at the North Pole has been measured at 4,261 m (13,980 ft). The nearest land is usually said to be Kaffeklubben Island, off the northern coast of Greenland about 700 km (430 mi) away, though some perhaps non-permanent gravel banks lie slightly closer.

The Earth’s North Magnetic Pole is the point on the surface of the Northern Hemisphere at which the Earth’s magnetic field points vertically downwards (i.e., the "dip" is 90°). Though geographically in the north, it is, by the direction of the magnetic field lines, physically a magnetic south pole. The North Magnetic Pole should not be confused with the Geographic North Pole, or with the lesser known North Geomagnetic Pole described later in this article.

The North Magnetic Pole moves slowly over time due to magnetic changes in the Earth’s core. In 2001, it was determined by the Geological Survey of Canada to lie near Ellesmere Island in northern Canada In 2009, it was moving toward Russia at almost 40 miles (64 km) per year.

The North Pole’s southern hemisphere counterpart is the South Magnetic Pole. Because the Earth’s magnetic field is not exactly symmetrical, the North and South Magnetic Poles are not antipodal: a line drawn from one to the other does not pass through the centre of the Earth; it actually misses by about 530 km (330 mi). The Earth’s North and South Magnetic Poles are also known as Magnetic Dip Poles, with reference to the vertical "dip" of the magnetic field lines at those points.



To quote from this article please cite:

MacFarlane, John M. (2016) Some North Polar Geography. Nauticapedia.ca 2016. http://nauticapedia.ca/Articles/Polar_Geography.php

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