"Because Earth is flat"...
Ok, let's see:
Sun is 5005 km above the surface.
During Lahaina Noon, directly overhead, has angular diameter of 0.53 degrees.
So, diameter of Sun is 2 * (5005 * tan(0.53 / 2) ) = 46.3 km.
For sunset Sun still has angular diameter of 0.53 degrees.
Since it didn't change the size, it means "atmospheric lensing" makes it look bigger.
Flat Earth makes top of the atmosphere flat as well.
Where the "atmospheric lensing" comes from, if the air isn't lense shaped?I also don't know of any observation or measurement that shows top of the atmosphere to be Fresnel lens shaped.
Maybe someone does?
Eye resolution is, roughly, one arc minute, which is 0.0167 degrees.
Vanishing point for object 46.3 km in diameter is (46.3 / 2) / tan(0.0167 / 2) = 158 850 km.
There are two reasons for Sun to never reach distance of 158 850 km from observer.
One, "atmospheric lensing" keeps it at 0.53 degrees.
Two, there is not enough room on Flat Earth for anyone to ever be that far from Sun.
For December solstice Sun is 12 605 km from North pole.
The very opposite end of the Earth at Ice wall is 32 605 km away.
At that distance Sun's elevation would be arctan(5005 / 32605) = 8.73 degrees.
Direct distance would be sqrt(32605
2 + 5005
2) = 32 987 km,
with angular diameter of 2 * arctan((46.3 / 2) / 32 987) = 0.08 degrees (4.8 arc minutes)
without "atmospheric lensing".
So, the only way is if "something" (horizon?) hides Sun from view for sunrise and sunset.
Air layers have a bit higher refraction index than vacuum above.
The lower the sunlight goes, the thicker the layers get, and it makes the light bend
downwards.
For Sun to stay 5005 km and look like setting we need sunlight to bend upwards, and that's what we don't have.
And it should be upwards most of the time for arctan(5005 / 10000) = 26.6 degrees.
You can hate these facts as much as you want,
you can ignore them,
sweep them under the carpet,
twist them and blur them,
run and hide from them,
they still won't disappear.
Let me remind you:
Atmospheric refraction of the light from a star is zero in the zenith,
less than 1′ (one arc-minute) at 45° apparent altitude, and still only 5.3′ at 10° altitude;
it quickly increases as altitude decreases, reaching 9.9′ at 5° altitude, 18.4′ at 2° altitude,
and 35.4′ at the horizon.
(from:
https://en.wikipedia.org/wiki/Atmospheric_refraction)