"Horizon" is only a human language, human with eyes sight scale.
What on earth do you mean by that?
The
horizon is the apparent line between the
sky and either the
land or the
sea, but it is very easy to see even if there are clouds, as in:
From equator a little light showed up for the first time at (before) 5 AM and the sun appears at around 6 AM. At 5 AM the position of the little light is about -45°. And sun appears at around -22.5°. We NEVER see the sun rises from horizon. Sun always appears from Above The Clouds.
Well, that is not the case everywhere. The sun often rises from and sets behind a clear sharp horizon as in this sunset.
So I conclude: The sun's ray refracts or bends. Even at 6 PM we see from left side of the sun: some lines with different angles from sun's light line.
This conforms that the sun we see is only the reflected sun ray. While the real sun gives rays towards other mediums so that we see different ray lines on sky.
Nothing that I see or is evident in those photos would indicate that.
The real position of the sun is distorted by some factors.
Either clouds, ceiling above the sun as well as below the sun.
What would distort the "real position of the sun", other than a very small amount of refraction?
We cannot assume the sky is vacuum. So complicated reality manifest n researches are on process to crack it.
The atmosphere is very thin even at 120,000 ft, than some balloons reach, so it certainly seems logical that up much higher it is very close a vacuum.
Besides numerous sounding rockets have measured the density of the atmosphere at extremely high altitudes.