Terrain visibility analysis
Can you see Mont Blanc from Lyon?
This analysis connects a studied point in central Lyon to the Mont Blanc summit and details the parameters governing this long-distance sight line.
Short answer: Yes. For the studied point in central Lyon, the 4,807 m summit clears the modelled terrain horizon across a 158 km sight line.
This page explains a reproducible Sightelo case. The result is recalculated on demand with the available elevation data; it is not a guaranteed real-world observation.
Open and recalculate this analysisPoints and assumptions
- Observation point
- Lyon, France
- Point of interest
- Mont Blanc, France/Italy
- Geodesic distance
- 158.0 km
- Initial bearing
- 86.5° (east)
- Refraction
- Standard (k = 0.13)
Terrain profile and line of sight
Detailed profile
Scroll horizontally to explore the full profile on a small screen.
- Calculated terrain
- Observer–summit sight line
- Minimum visibility line
- 0 m reference (modelled curvature)
At the summit, the target clears the modelled horizon by 932.4 m. No blocking terrain is calculated. The relief forming the horizon is 155.119 km from A.
Calculated profile values
| Distance (km) | 158.0 km |
|---|---|
| Observer eye altitude | 183.7 m |
| Summit altitude | 4807.3 m |
| Minimum visible target altitude | 3874.9 m |
| Target margin above the modelled horizon | +932.4 m |
| Minimum local sight-line clearance | +15.0 m |
| Displayed / calculated samples | 498 / 1582 |
| Excluded around A / B | 200 m / 1500 m |
| Horizon-forming relief | 155.1190 km |
Audited calculation: 2026-10-09. The interactive calculator can recalculate with currently available elevation data.
Can Mont Blanc really be seen from Lyon?
Yes. The Sightelo model classifies the summit as visible from the studied point in Lyon: it clears the horizon formed by intervening terrain. This theoretical terrain visibility does not guarantee a naked-eye observation.
How far is Mont Blanc from Lyon?
The coordinates in this example give a geodesic distance of 158.0 km. At this scale, distant terrain, Earth curvature and atmospheric refraction all affect the sight line.
What conditions are needed to see Mont Blanc from Lyon?
A real observation requires a clear horizon and sufficiently transparent air. Haze, clouds, buildings and trees are not modelled, and actual refraction may differ from the standard assumption.
How does Sightelo calculate this visibility?
Sightelo samples terrain between the two coordinates, applies Earth curvature and standard refraction with a coefficient of 0.13, then compares that profile with the line towards the supplied 4,807.3 m summit elevation.