Classifications
lenticular
Graticule
Meridians: Central meridian is straight. Other meridians are curved, equally spaced along the equator and concave toward the central meridian.
Parallels: Equator and the poles are straight. Other parallels are curved, equally spaced along the central meridian and concave toward the nearest pole.
Poles: Straight lines about 0.4 as long as the equator, depending on the latitude of the standard parallels of the base equidistant cylindric projection.
Symmetry: About the central meridian or the equator.
Scale
True along the central meridian. Constant along the equator.
Distortion
Moderate except near outer meridians in polar regions.
Other features
Equally spaced central meridian and equator.
Usage
Whole-world maps.
Origin
Presented by Oswald Winkel (1873-1953) of Germany in 1921. Obtained by averaging coordinates of equidistant cylindric and Aitoff (not Hammer-Aitoff) projections. Winkel applied the name “Tripel”, normally meaning triple.
Description adapted from J.P. Snyder and P.M. Voxland, An Album of Map Projections, U.S. Geological Survey Professional Paper 1453. United States Government Printing Office: 1989.