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Angle on the horizontal plane between magnetic north and true north. Example of magnetic declination showing a compass needle with a "positive" (or "easterly") variation from geographic north. N g is geographic or true north, N m is magnetic north, and δ is magnetic declination. Magnetic declination (also called magnetic variation) is the ...
The geomagnetic north pole is the northern antipodal pole of an ideal dipole model of the Earth's magnetic field, which is the most closely fitting model of Earth's actual magnetic field. The north magnetic pole moves over time according to magnetic changes and flux lobe elongation [2] in the Earth's outer core. [3]
Its angle relative to true North is the declination (D) or variation. Facing magnetic North, the angle the field makes with the horizontal is the inclination ( I ) or magnetic dip . The intensity ( F ) of the field is proportional to the force it exerts on a magnet.
The first is magnetic declination or variation—the angular difference between magnetic North (the local direction of the Earth's magnetic field) and true North. [1] The second is magnetic deviation—the angular difference between magnetic North and the compass needle due to nearby sources of interference such as magnetically permeable bodies ...
Magnetic dip causes the compass to dip upward or downward depending on the latitude. Magnetic dip, dip angle, or magnetic inclination is the angle made with the horizontal by Earth's magnetic field lines. This angle varies at different points on Earth's surface. Positive values of inclination indicate that the magnetic field of Earth is ...
The magnetic compass is very reliable at moderate latitudes, but in geographic regions near the Earth's magnetic poles it becomes unusable. As the compass is moved closer to one of the magnetic poles, the magnetic declination, the difference between the direction to geographical north and magnetic north, becomes greater and greater.
Compass rose with the eight principal winds. A compass rose or compass star, sometimes called a wind rose or rose of the winds, is a polar diagram displaying the orientation of the cardinal directions (north, east, south, and west) and their intermediate points. It is used on compasses (including magnetic ones), maps (such as compass rose ...
World Magnetic Model. Magnetic declination map at sea-level for the year 2010 derived from WMM2010. The World Magnetic Model (WMM) is a large spatial-scale representation of the Earth's magnetic field. It was developed jointly by the US National Geophysical Data Center and the British Geological Survey. The data and updates are issued by the US ...