On a map, time zones are marked by lines of longitude.

在地图上，时区由经线标记。

Ptolemy built his grid out of lines we still use today: 180 lines of latitude and 360 lines of longitude.

托勒密用我们今天仍在使用的线构建了他的网格：180 条纬线和 360 条经线。

But unfortunately, these winter Atlantic storms simply don't make it far enough to bring their moisture to the Western Plains beyond the 98th and 100th meridian lines of longitude.

但不幸的是，这些冬季大西洋风暴根本不足以将它们的水分带到子午线 98 度和 100 度以外的西部平原。

If we draw this route on a flat map, it passes through every line of longitude at a different angle.

如果我们在平面地图上绘制这条路线，它会以不同的角度穿过每条经线。

And the line he drew to mark the boundary between the more wet East and the more arid West was the 100th meridian line of longitude here which was more or less correct.

他在这里画了一条线，标出了比较潮湿的东部和比较干旱的西部之间的分界线，这条线在子午线 100 度上，大致正确。