Meridional parts at a given latitude - the core quantity behind Mercator sailing and chart construction.
Formula
$$ M = 7915.704 \cdot \log_{10}\left[\tan\left(45 + \tfrac{\varphi}{2}\right)\right] - 23.013 \cdot \sin\varphi $$
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| $φ$ | Latitude | ° | chart / GPS |
| $M$ | Meridional parts at latitude φ | - | result |
Sources
- Bowditch - Meridional parts.
- Norie’s Tables 41.