Meridianbøyden

Meridianbøyden, literally the bending of the meridian, is a term used in geodesy and cartography to describe how lines of longitude (meridians) appear or behave when the Earth's curved surface is represented on a plane or within a different coordinate system. On a globe, meridians are great-circle routes from the North Pole to the South Pole; when mapped, their appearance depends on the projection, centers, and datum used, which can cause meridians to curve, converge, or deviate from their true geometry.

In map projections, the way meridians are drawn determines the extent and nature of meridian bending. Some projections render meridians as straight lines, while others cause them to bend toward or away from the projection center, or to converge at the edges of the map. The observed bending is a manifestation of projection distortion and the need to trade off properties such as angle preservation, area accuracy, or distance fidelity. The concept also intersects with the use of different datums and ellipsoids, which influence the reference shape of the Earth and thus affect how meridians map to a flat plane.

Meridianbøyden is most relevant in practical tasks such as surveying, GIS coordinate transformations, and map design, where understanding how meridians deviate informs decisions about projection choice, datum alignment, and error assessment. It is less a physical phenomenon and more a characterization of how a chosen map representation distorts the true geographic grid.

See also: longitude, meridian, map projection, geodesy, databasing and coordinate systems.