Spatial distance The previous distance measures are
based on the concept of distance in two dimensions. For
small areas like cities or counties, this is a reasonable
simplification. For longer distances such as those that
span larger countries or continents, measures based on
two dimensions are no longer appropriate, since they fail
to account for the curvature of the earth. Consequently,
global distance measures need to use the gratitude, the
co-ordinate system comprised of latitude and longitude
along with special formulae to calculate the distances.