The graticule described is for a polar aspect.
Meridians: Equally spaced semicircles from pole to pole, concave toward the west.
Parallels: Concentric circles.
Pole: The central pole is a point; the other pole is a bounding circle.
Symmetry: Radially about the center point.
This equal-area projection is a novelty map, usually centered at a pole, showing semicircular meridians in a pinwheel arrangement. Scale is correct along the meridians. This projection is not conformal.
There are no standard parallels for azimuthal projections.
Data greater than 65º distant from the center point is trimmed.
landareas = shaperead('landareas.shp','UseGeoCoords',true); axesm ('wiechel', 'Frame', 'on', 'Grid', 'on'); geoshow(landareas,'FaceColor',[1 1 .5],'EdgeColor',[.6 .6 .6]); tissot;