An isometric latitude is an authalic latitude which is directly proportional to the spacing of parallels of latitude
from the equator on an ellipsoidal Mercator projection.
It is defined by
(1)
where the symbol
is sometimes used instead of . The isometric latitude is related to the conformal
latitude by
Adams, O. S. "Latitude Developments Connected with Geodesy and Cartography with Tables, Including a Table for Lambert Equal-Area
Meridional Projections." Spec. Pub. No. 67. U. S. Coast and Geodetic
Survey, 1921.Snyder, J. P. Map
Projections--A Working Manual. U. S. Geological Survey Professional
Paper 1395. Washington, DC: U. S. Government Printing Office, p. 15, 1987.