Terrain visibility analysis
Mount Rainier from Seattle
A 94 km sight line from Seattle towards Mount Rainier, crossing the Puget Sound lowlands before reaching the Cascade foothills.
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
- Seattle, United States
- Point of interest
- Mount Rainier, United States
- Geodesic distance
- 94.3 km
- Initial bearing
- 152.5° (south-southeast)
- 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 136.9 m. No blocking terrain is calculated. The relief forming the horizon is 92.940 km from A.
The calculation models terrain, Earth curvature and standard atmospheric refraction. It does not model buildings, trees, clouds, haze or local atmospheric variations.
Calculated profile values
| Distance (km) | 94.3 km |
|---|---|
| Observer eye altitude | 60.7 m |
| Summit altitude | 4392.0 m |
| Minimum visible target altitude | 4255.1 m |
| Target margin above the modelled horizon | +136.9 m |
| Minimum local sight-line clearance | +29.7 m |
| Displayed / calculated samples | 498 / 945 |
| Excluded around A / B | 200 m / 900 m |
| Horizon-forming relief | 92.9404 km |
Audited calculation: 2026-10-16. The interactive calculator can recalculate with currently available elevation data.
What this example helps you study
The low terrain around Seattle initially leaves a broad southern horizon, but foothill ridges rise quickly on the approach to Rainier. Compare the terrain result with the volcano's familiar real-world prominence, where cloud cover often becomes the decisive limitation.
Limits of interpretation
The calculation models terrain, Earth curvature and standard atmospheric refraction. It does not model buildings, trees, clouds, haze or local atmospheric variations.