The 3 big lies: atmosphere, gravity, refraction

I send you a link with air refraction experiments.

These examples are from Harvard University, but there are many others



Schlieren Optics
Harvard Natural Sciences Lecture Demonstrations

It can be observed with the method of Schlieren. The basic idea is that a minimal effect is "amplified" by a parabolic mirror.

By setting the mirror twice the focal distance from the light source, the rays should be collected and sent back to their source. By using a filter (knife-edge in the video) all you need is a minimal deviation, in order for the rays to be "cut off" - this corresponds to the darker edges.

This video explains how it works and how to build it at home:



How To: Build Your Own Schlieren Setup
JoshTheEngineer


You can also see the wikipedia page:
en.wikipedia.org/wiki/Schlieren_photography

and this other web page:
www.ian.org/Schlieren/HowTo.html

This experiment, that anyone can repeat at home, shows that masses of air of different pressure, temperature, or chemical composition are capable of deviating the light rays.

It is a very small effect that normally we do not notice, but also a small deviation gives the important effects for rays that travel Kilometers.

For example, two rays which are deflected by an angle X, and after a meter are distant one millimeter, after one kilometer will be distant one meter. The distance linearly increases by a fixed angle of deviation.

I also found another video by flat earthers, where they discuss this fact:



Zeteticism FLAT EARTH Vol 1 The Chicago Skyline Light Refraction & the Illusion of Curvature
dlees

He uses the air refractive index to explain the fact that the buildings disappear below the horizon (in the video there are photos of Chicago).

The error in this video is that if the rays are deflected downwards, * objects appear higher * than they really are (see
the example in the video with the image of the sun). But he would like to say that in fact we see them further down! This is a key point of the video. Aside from misinterpreting all the results, he says a few things that are correct.

The other thing I do not understand is that the tables for observations of radars already take into account the curvature of the earth. So they explain the effects of refraction (that is, objects that appear at the top of what they really are) considering the curvature of
land.

There is also a link to another video of a channel for engineers, where they explain the correct formula to calculate the apparent height
of buildings accounting for air refraction. In this sense, the calculation usually done by flat earthers involving the distance and the curvature of the earth is not correct, but can be corrected with the method explained in the video.

Although I did not watch the whole video and checked all the details, I think this effect of refraction reduces the "apparent curvature" by 1/7, that is approximately 14%.

You could try to make a guesstimate with this 14% correction and see if it explains seeing Corsica from Ventimiglia.