Atmospheric refraction causes a distant object to appear higher than its actual position. As a result, the object can be physically behind Earth’s curvature but is still visible because the light coming from it is refracted by the atmosphere.
There are many curvature calculators and simulation tools that don’t account for refraction. They would give us the correct results indicating the object’s physical positions but fail to show us the correct apparent position of the object when visually observed.
Flat-Earthers are often too happy with the calculator showing them the results they want to see and fail to see the reason for the discrepancy.
To do this ‘research’, flat-Earthers would start from observation or existing pictures. Then they would try to input the observer’s and the object’s height and distance to an online curvature calculator. If the object is visible, but according to the calculator it should be entirely behind the horizon, then they would very quickly conclude “the curvature doesn’t exist.”
They are wrong. The discrepancy is caused by the fact that the calculator does not account for atmospheric refraction.
Atmospheric is dynamic, and so is the refraction caused by it. The degree of refraction changes depending on the weather. Most curvature calculators that account for refraction provide a function for us to input the degree of refraction to the calculator.
Ironically, many of these observations and pictures clearly show that Earth’s curvature obstructs the bottom parts of the objects, yet for some reason, they fail to see that. Those facts are more than enough for us to conclude the object is behind Earth’s curvature, even if the upper parts of the objects are visible.
Some Popular Online Curvature Calculators
These do not account for refraction:
- Earth Curve Calculator (dizzib.github.io)
- Earth Curvature Calculator (earthcurvature.com)
- GeoGebra Horizon Calculator (geogebra.org)
These ones do: