A Gaussian grid is used in the earth sciences as a gridded horizontal coordinate system for scientific modeling on a sphere (i.e., the approximate shape of the Earth).
The grid is rectangular, with a set number of orthogonal coordinates (usually latitude and longitude).
On the contrary along a longitude (or meridian) the gridpoints are unequally spaced.
The spacing between grid points is defined by Gaussian quadrature.
[further explanation needed] By contrast, in the "normal" geographic latitude-longitude grid, gridpoints are equally spaced along both latitudes and longitudes.