 # From Riva di Traiano you can see Giannutri?

The answer is no! and there is a reason you should know if you go to sea!

The marine horizon is the circle with the observer at the center and the radius is the distance between the observer and the meeting line between the atmosphere and the surface of the sea. To determine the distance of the marine horizon, the formula is solved: D = 2,08 √e, dove (and) is the height of the observer's eye above sea level. The visible distance depends on the observer's height above sea level e, in theory, the observer should be able to see up to the point of tangency of the line of his view with the sea surface, but the refraction due to the earth's atmosphere has the effect of “bend” the view, increasing its radius. Refraction is the deviation that a ray of light undergoes as it passes through different elements, in this case the layers of the atmosphere.

For further information: https://it.wikipedia.org/wiki/Orizzonte

If we take our case, considering the Riva di Traiano tower as an observation point (10mt slm) and we apply the necessary formulas we will realize that the island of Giannutri (Poggio by Capel Rosso 89,4 m) falls within the non-visible portion of the horizon even considering the effect of refraction

Download the Excel sheet for calculating the distance of the horizon and the visibility between two points

Below is a summary graphic