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Magnetic dip causes the compass to dip upward or downward depending on the latitude. Illustration of magnetic dip from Norman's book, The Newe Attractive. 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.
With a local declination of 14°E, a true bearing (i.e. obtained from a map) of 54° is converted to a magnetic bearing (for use in the field) by subtracting declination: 54° – 14° = 40°. If the local declination was 14°W (−14°), it is again subtracted from the true bearing to obtain a magnetic bearing: 54°- (−14°) = 68°.
A typical procedure for measuring its direction is to use a compass to determine the direction of magnetic North. 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.
By the 1940s, magnetic north had moved northwest from its 1831 position by about 250 miles (400 kilometers). In 1948, it reached Prince Wales Island, and by 2000 it had departed Canadian shores.
Magnetic declination from true north in 2000. Historically, the magnetic compass was an important tool for navigation. While it has been widely replaced by Global Positioning Systems, many airplanes and ships still carry them, as do casual boaters and hikers. [28] The direction in which a compass needle points is known as magnetic north.
Robert Norman is noted for The Newe Attractive, a pamphlet published in 1581 [1] describing the lodestone and practical aspects of navigation.More importantly, it included Norman's measurement of magnetic dip, the incline at an angle from the horizon by a compass needle discovered by Georg Hartmann in 1544.
Like the North Magnetic Pole, the North Geomagnetic Pole attracts the north pole of a bar magnet and so is in a physical sense actually a magnetic south pole. It is the center of the 'open' magnetic field lines which connect to the interplanetary magnetic field and provide a direct route for the solar wind to reach the ionosphere.
Magnetometers used to study the Earth's magnetic field may express the vector components of the field in terms of declination (the angle between the horizontal component of the field vector and true, or geographic, north) and the inclination (the angle between the field vector and the horizontal surface). [5]