<P> A ( geographical ) meridian ( or line of longitude ) is the half of an imaginary great circle on the Earth 's surface , terminated by the North Pole and the South Pole , connecting points of equal longitude . The position of a point along the meridian is given by its latitude indicating how many degrees north or south of the Equator the point is . Each meridian is perpendicular to all circles of latitude . Each is also the same length , being half of a great circle on the Earth 's surface and therefore measuring 20,003.93 km ( 12,429.9 miles ) . </P>
<P> A ( geographical ) meridian ( or line of longitude ) is the half of an imaginary great circle on the Earth 's surface , terminated by the North Pole and the South Pole , connecting points of equal longitude . The position of a point along the meridian is given by its latitude indicating how many degrees north or south of the Equator the point is . Each meridian is perpendicular to all circles of latitude . Each is also the same length , being half of a great circle on the Earth 's surface and therefore measuring 20,003.93 km ( 12,429.9 miles ) . </P>
what is the imaginary line running north and south
what is the imaginary line running north and south
( geographical ) meridian line of longitude
( geographical ) meridian line of longitude