虽然我们在日常生活中无需手动计算经度，但理解子午线在几何学中的本质，对理解它的重要性至关重要。
Meridian longitude provides a crucial spatial framework that bridges geography and time. From facilitating global trade routes to enabling GPS technology in our smartphones, these imaginary north-south lines are fundamental to how we navigate and organize our world. meridian longitude
Airplanes and cargo ships use digital charts based on the World Geodetic System (WGS 84), which relies heavily on the traditional longitude grid. Pilots and captains map out great-circle routes—the shortest distance between two points on a sphere—by calculating changes across meridians. 3. Geographic Information Systems (GIS) meridian longitude