Meridian Longitude =link=

The Grid of the World: Understanding Meridians and Longitude

A meridian is half of a great circle that connects the North and South Poles. All points on the same meridian share the same longitude. meridian longitude

• Your chronometer says it is 12:00 noon in Greenwich.
• Locally, the sun reaches its zenith (noon) at 2:00 PM by your chronometer.
• The 2-hour difference × 15° per hour = 30° West longitude.

“Meridian longitude” is therefore a tautology: all meridians are lines of longitude, and every longitude value corresponds to a specific meridian (except the anti‑meridian, 180°). The Grid of the World: Understanding Meridians and