Therefore every meridian is the same length. Size decreases from the equator toward the poles. The International Date Line is a line that partly corresponds to the 180th meridian. It is a line that extends through the middle of the Pacific Ocean. See Figure 2.3 on page 21 of the text for the location and change of day that results.
Maps are two dimensional, selective, reduced and distorted images of the earth.
They are distorted because, being two dimensional, they are attempting to represent the real three dimensional earth. Map projections are necessary in order to control, reduce or eliminate some or most of the distortion in using a two dimensional object to represent a three dimensional object. Map projections can control or reduce or eliminate distortion in one or more of these properties. Be familiar with the characteristics of latitude and longitude . See Figures 2.1, 2.2, 2.4, pages 19 - 21. 2.