# Albers Conical Equal Area

A conic, equal area projection.

Scale

True along the one or two chosen standard parallels, which are usually but not necessarily specified on the same side of the Equator. As a rule of thumb, these parallels can be placed at one-sixth and five-sixths of the range of latitudes, but there are more refined means of selection.

Scale is constant along any given parallel. The scale factor at any given point along the meridian is the reciprocal of that along the parallel, to preserve area.

Distortion

Free of angular and scale distortion only along the one or two standard parallels. Distortion is constant along any given parallel.

Usage

Frequently used in the ellipsoidal form for maps of the United States in the National Atlas of the United States, for thematic maps, and for world atlases. Also used and recommended for equal-area maps of regions that are predominantly east-west in extent.

Limitations

Normally used only for a single hemisphere.

Origin

Presented by Heinrich Christain Albers (1773-1833) of Germany in 1805.

Limiting Forms

Polar Lambert Azimuthal Equal-Area projection: if a pole is made the single standard parallel. The cone of projection thereby becomes a plane.

Lambert Equal-Area Conic projection: if the pole and another parallel are made the two standard parallels.

Lambert Cylindrical Equal-Area projection: if the Equator is the single standard parallel. The cone of projection thereby becomes a cylinder.

Behrmann or other cylindrical equal-area projections: if the two standard parallels are symmetrically placed north and south of the Equator.

Options

Specify the first standard parallel and second standard parallel to tailor the projection to the area to be mapped.

Specify the latitude origin and longitude origin to center the map projection to the area to be mapped. Specifying a non-Equatorial origin causes an oblique projection.