Meridians are lines of what?

Meridians are defined as lines of longitude, which run from the North Pole to the South Pole. They are used to measure the angular distance of a point east or west of the Prime Meridian, which is established at 0 degrees longitude. Each meridian represents a vertical line on the globe, indicating how far a location is from the reference line. This is foundational in understanding the Earth's coordinate system, which divides the planet into various longitudinal sections.

In contrast, the lines of latitude, which run horizontally around the Earth, measure the distance north or south of the equator. Altitude refers to elevation above sea level, and area is a measurement of space, neither of which pertains to the concept of meridians. Thus, recognizing meridians as lines of longitude is essential for accurate navigation and the establishment of geographical coordinates in GIS applications.