This image is the result of a Refraction Simulation for the globe and flat earth model.
Globe: Standard Refraction bends light rays in an arc downwards, so the globe appears less curved and the horizon appears above the cyan line indicating the geometric horizon.
Flat Earth: As the simulations shows the flat earth would appear concave and there would be no distinct horizon line. The surface would simply fade into the sky with distance.
The simulation simulates a visibility of 200 km. This means that at 200 km only 50% of the light gets to the observer. At another 200 km only 25% ect.
The Simulation of Atmospheric Refraction renders scenes as seen on atmospheric conditions you can provide. It is an accurate simulation of Atmospheric Refraction for both Globe Earth and Flat Earth, using ray tracing to calculate each individual light ray an observer perceives, by bending it according to the atmospheric conditions (refraction) along the path of each light ray.
The Simulation is based on a mathematical model of the atmosphere, derived from basic physical laws, confirmed by uncountable measurements in geodetic survey and many experiments.