Two standard parallels are selected to be equidistant from the equator. Used often for marine navigation because all straight lines on the map are lines of constant azimuth. The Mollweide projection is a pseudocylindrical projection which resembles cylindrical projections in that parallel latitude lines are straight, but lines of longitute are curved. The Mollweide is equal-area and its central meridian is straight. The 90th meridians are circular arcs.
Parallels are straight, but unequally spaced.
Non-Stereographic Projection Stereographic projections are used for navigation in polar regions. The directions are true from the center point and scale increases away from the center point as does distortion in area and shape. Sinusoidal Projection Sinusoidal equal-area projections have straight parallels at right angles to a central meridian and the parallels.