is in principle the angle made by the needle of a vertically held compass, though in practice ordinary compass needles may be deliberately weighted against This glossary of geography terms is a list of definitions of terms and concepts used in geography and related fields, including Earth science, oceanography, cartography, and human geography, as well as those describing spatial dimension, topographical features, natural resources, and the collection, analysis, and visualization of geographic data. It is split across two articles: This page, Glossa eq… magnetic dip Also dip angle and magnetic inclination. The angle made with the horizontal by the Earth's magnetic field lines. Locations in the Northern Hemisphere usually have positive values of inclination, indicating that the magnetic field is angled downward, into the Earth; the angle increases as one approaches the North Magnetic Pole, where the field lines point vertically downward, perpendicular to the horizontal. Locations in the Southern Hemisphere usually have negative inclination, indicating that the field lines are angled upward, away from the Earth, with the maximum angle located at the South Magnetic Pole. Dip angle is in principle the angle made by the needle of a vertically held compass, though in practice ordinary compass needles may be deliberately weighted against dip, or may be unable to move freely in the correct plane. Magnetic dip can be measured more reliably with a dip circle.