Dip of the Sea Horizon. Dip, Depression or Inclination of the Visible Horizon (Dip of the Sea Horizon) is the vertical angle between the True Horizon Plane and the direction to the Visible Horizon.
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.