Meridian (geography)

For the astronomical concept, see Meridian (astronomy). For other uses, see Meridian.
Meridians run between the North and South poles.

In geography and geodesy, a meridian is the locus connecting points of equal longitude, which is the angle (in degrees or other units) east or west of a given prime meridian (currently, the IERS Reference Meridian).[1] In other words, it is a coordinate line for longitudes, a line of longitude. The position of a point along the meridian at a given longitude is given by its latitude, measured in angular degrees north or south of the Equator. On a Mercator projection or on a Gall-Peters projection, each meridian is perpendicular to all circles of latitude. Assuming a spherical Earth, a meridian is a great semicircle on Earth's surface. Adopting instead a spheroidal or ellipsoid model of Earth, the meridian is half of a north-south great ellipse. The length of a meridian is twice the length of an Earth quadrant, equal to 20,003.93 km (12,429.87 mi) on a modern ellipsoid (WGS 84).[2]

  1. ^ Withers, Charles W. J. (2017). "Absurd Vanity". Zero Degrees. Harvard University Press. pp. 25–72. doi:10.4159/9780674978935-004. ISBN 978-0-674-97893-5. JSTOR j.ctt1n2ttsj.6.
  2. ^ Weintrit, Adam (2013). "So, What is Actually the Distance from the Equator to the Pole? – Overview of the Meridian Distance Approximations". TransNav. 7 (2): 259–272. doi:10.12716/1001.07.02.14.