Distance of the Sea Horizon.
Distance of the sea horizon is greater than the geometric distance to the horizon because:
Earth’s atmosphere is not all the same density. It is denser at the surface of the earth and decreases with altitude.
So, the sight that penetrate the atmosphere with different densities are diverted from their original direction.
Then, the Sea Horizon will be seen in a different direction than that which is found in reality.
This is called Terrestrial Refraction.
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