What shape is used in a Lambert projection?

The Lambert projection is a type of conic projection, meaning it uses a cone as its projection surface. In this projection method, the Earth's surface is projected onto a cone that is placed over a portion of the sphere. This is particularly useful for mapping areas with larger east-west than north-south extents because it can maintain accurate shapes and areas within the specific region that is being mapped.

The Lambert projection is commonly employed in aeronautical and meteorological mapping, where preserving the angles and distances within the specified bounds is critical. These characteristics make the conic projection ideal for countries and regions that are more elongated in the east-west direction.

Other projection shapes, such as the plane (which corresponds to azimuthal projections) or the cylinder (typical for cylindrical projections like the Mercator), do not offer the same level of accuracy for certain geographic areas as the Lambert projection does when dealing with a large amount of east-west geography. The ellipse, while a shape that appears in some other mapping contexts, is not used in the Lambert projection since this projection focuses on a conic surface.