Terrestrial Meridian

terrestrial meridian

[tə′res·trē·əl mə′rid·ē·ən]

Meridian, Terrestrial

 

an imaginary line on the surface of the earth all of whose points have the same geographic longitude; this imaginary line passes through both poles of the earth. Terrestrial meridians for the earth’s ellipsoid of revolution are plane curves—arcs of ellipses that are sections of an ellipsoid cut by planes passing through the axis of revolution. Geographic latitude is measured along the terrestrial meridian, north of the equator being northern latitude and south of the equator being southern latitude. The total length of a terrestrial meridian (circumference of the earth) for the Krasovskii ellipsoid is 40,-008.550 km. (SeeGEOGRAPHIC COORDINATES.)

References in classic literature ?
The same thing happened to a French savant among the mountains of Spain, when he was measuring the terrestrial meridian.
Projecting it down to the surface of the Earth, we get a local terrestrial meridian that is really just part of a circle of longitude.

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