Meridian, also known as meridian, is an auxiliary line assumed by human beings for the convenience of measurement, and is defined as a semi-circular arc on the great circle connecting the north and south poles on the earth's surface. Any two meridians are equal in length and intersect at the North Pole and the South Pole.
Each meridian has its corresponding numerical value, called longitude, which indicates the east-west position.
Meridian, also called meridian, is a line connecting the two poles on the ground, indicating the north-south direction. The longitude line and the latitude line perpendicular to it constitute the coordinates on the earth, that is, the latitude and longitude network. The position anywhere on the earth can be represented by the intersection of a longitude line and a latitude line. All meridians are equal in length.