Solar eclipse in Monterroso

The terrain

The horizon at Monterroso in the Sun's direction

1. In the direction the Sun will be in at maximum, the ground rises 1.0° above the horizontal at Monterroso: a rise of 611 m, 3 km away, with the reference point of the municipality 555 m above sea level.
2. At that same moment the Sun will be 11.4° above the horizon at Monterroso. That is the APPARENT altitude: it already includes atmospheric refraction, which close to the horizon lifts the disc by a couple of tenths of a degree, which is why it does not match the geometric altitude in the card above to the decimal.
3. The subtraction leaves 10.4° of margin. The Sun's disc is half a degree across, so the Sun will sit about 20 solar discs above the terrain profile: in that direction the relief is not what decides. What can block it at that height is what this calculation does not see.

This calculation looks ONLY at bare ground: it does not see buildings, sheds or trees. In a village or a city, the building across the street blocks more than the ridge in the distance. It sweeps 60 km all around with cells of about 28 metres and starts looking 300 metres out from the point, which is the distance at which you are no longer looking at your own roof. And the point is the reference point of the municipality: 500 metres away the number shifts by several degrees.

Elevation model served by AWS Terrain Tiles (terrarium format) at zoom 12: about 28 metres per cell at the latitude of Spain. Checked against the IGN's MDT25 (PNOA-LiDAR), the official Spanish model, in 21 municipalities spread along the path (coast, islands, plateau, closed valley and city): the median difference is 0.0° and 20 of the 21 fall within half a degree. Produced using Copernicus data and information funded by the European Union — EU-DEM layers.