What is the primary purpose of lines of longitude?

The primary purpose of lines of longitude is to represent how far east or west a location is from the prime meridian, which is designated as 0 degrees longitude. Lines of longitude run from the North Pole to the South Pole and are measured in degrees up to 180 degrees east or west. This system allows for precise geographical positioning and navigation, as it helps to identify specific locations on the Earth's surface based on their angular distance from the starting point of the prime meridian.

In contrast, other purposes related to latitude and climate or seasonal changes are not functions of longitude. Lines of latitude are used to measure distance north and south of the equator, indicating how far a place is from the equator. Seasonal changes and climate indicators are generally linked to both latitude and geographic features rather than longitude alone. Thus, recognizing the specific role of lines of longitude in defining east-west positioning is fundamental in geography.