Latitude and Longitude
Position on the Earth's surface is defined using latitude and longitude. Latitude measures north or south of the Equator (0° to 90°N or S). Longitude measures east or west of the Prime Meridian at Greenwich (0° to 180°E or W).
Each degree is divided into 60 minutes ('). One minute of latitude equals one nautical mile. Position is written as, for example: 50°24'.3N 001°12'.8W. On a chart, latitude is read from the vertical (side) scale and longitude from the horizontal (top/bottom) scale.
Key Points
- Latitude = N/S of Equator (0°–90°)
- Longitude = E/W of Greenwich (0°–180°)
- 1 minute of latitude = 1 nautical mile
- Always measure distance using the LATITUDE scale
- Format: 50°24'.3N 001°12'.8W
Tip: NEVER use the longitude scale to measure distance — only the latitude scale. One minute of longitude is NOT one nautical mile (it varies with latitude).