Latitude ( or ). It is measured in degrees, minutes and seconds or decimal degrees, north or south of the equator. The precise measurement of latitude requires an understanding of the gravitational field of the Earth, either to set up theodolites or to determine GPS satellite orbits. The study of the figure of the Earth together with its gravitational field is the science of geodesy. This article relates to coordinate systems for the Earth: it may be extended to cover the Moon, planets and other celestial objects by a simple change of nomenclature. The graticule is formed by the lines of
Equivalent latitude is the radius of the Earth. This method generates a mapping that is as continuous as the data allows as opposed to binning which produces a coarse-grained mapping. Equivalent latitude In differential geometry, the equivalent latitude is a Lagrangian coordinate . It is often used in atmospheric science, particularly in the study of stratospheric dynamics. Each isoline in a map of equivalent latitude follows the flow velocity and encloses the same area as the latitude line of equivalent value, hence "equivalent latitude." Equivalent latitude is calculated from potential vorticity, from passive tracer simulations and from actual measurements of atmospheric tracers