magnetic declination

"Magnetic North" redirects here, for other uses see Magnetic North (disambiguation)The magnetic declination (also known as grid magnetic angle in military circles) at any point on the Earth is the angle between the local magnetic field -- the direction the north end of a compass points -- and true north. The declination is positive when the magnetic north is east of true north. The term magnetic variation is equivalent, and is more often used in aeronautical and other forms of navigation. Isogonic lines are where the declination has the same value, and the lines where the declination is zero are called agonic lines.
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Noun
1. the angle (at a particular location) between magnetic north and true north
(synonym) magnetic variation, variation
(hypernym) angle

The angle between the magnetic and geographical meridians at any place, expressed in degrees east or west to indicate the direction of magnetic north from true north. In nautical and aeronautical navigation, the term magnetic variation is used instead of magnetic declination and the angle is termed variation of the compass or magnetic variation. Magnetic declination is not otherwise synonymous with magnetic variation which refers to regular or irregular change with time of the magnetic declination, dip, or intensity. See also declination; magnetic variation. 1/9/71

Angle horizontal, en un lieu et un temps donnés, entre la direction du nord géographique et celle du nord magnétique. La déclinaison magnétique est qualifiée est ou ouest selon que le nord magnétique se trouve à l'est ou à l'ouest du nord géographique. Voir aussi déclinaison astronomique; variation magnétique. 1/9/71

See: declination

DECLINAZIONE MAGNETICA