The question no flat-earther can answer

That one's easy; it's a matter of perspective. Your eyes can perceive angular distance, but not absolute distance. You are seeing the sun and moon from one point of a triangle; they are the other two. Anything along the side of that triangle, regardless of absolute distance from you, will appear to be the same angular distance apart from anything along the other side of the triangle, regardless of absolute distance.

then . . . distances in the southern Hemisphere are much greater between lines of latitude than distances between the same lines of latitude north of the equator.

But they are at the same level , not one higher or lower than the other...
I still don`t understand , so I won`t go any further because I don`t know lol...
...xox...

If the earth is flat, there can be no "southern hemisphere". On a disc, everything is on the same plane. "Hemisphere" means a partial spherical globe.

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If the earth is flat, there can be no "southern hemisphere". On a disc, everything is on the same plane. "Hemisphere" means a partial spherical globe.

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Ha! Of course you are right. So in the flat earth model, what is the southern hemisphere in the round earth model would be the outside half of the disc! (Not actually the outside half by area, but by length of radius!)

Yes. But if the sun is shining over THE WHOLE DISC, there are no hemispheres to discuss! And there would be no day/night cycle either. We would have continuous daylight.

The distance to which sunlight can be seen is limited by the atmosphere.

A good example to illustrate this idea is when fog "rolls in" and visibility drops to less than one mile. And, the sun is dim or not seen at all in the sky - covered over by the dense fog.

The moisture in the atmosphere becomes dense enough to "block" the sun - partially or completely.

Ever seen a really dark sky in the middle of the day because of the really heavy cloud cover? When the sun cannot be seen at all? When it is just almost as dark as night?

Moisture (and other things like smog, but mostly moisture) in the atmosphere can partially or completely dim/block the sun.

As the sun moves farther away, more of the atmosphere comes between you and the sun. Eventually, the sky dims and goes dark because the light of the sun can no longer reach you - because of the moisture (and other things) in the atmosphere.

I addressed this previously. Atmosphere, by itself, is very nearly transparent. While there is normally water vapour in the atmosphere, it is also transparent. When there is enough vapour, and there is enough of a temperature differential, fog forms. However, fog is not merely dense atmosphere! Pollution also is not atmosphere either, but an addition to it.

And, I am addressing it now.

Anything "added to" the atmosphere becomes a part of it. It is not simply an "air bubble" of mixed gases; rather, it is the space occupied by the "air bubble" - and everything in it - including water, factory chemicals, etc.

... which, in sufficient densities, do block the sun, but this still has nothing to do with the absolute disappearance of the sun once it is blocked by the horizon.

Correct - it has nothing to do with the Ball Earth Model -- because, I am explaining the disappearance of the sun according to the Flat Earth Model.

I know. The problem is that your explanation is inconsistent with real-world observations and is therefore wrong.

It is not.

I see the sun disappear over the horizon quite frequently, when there are no clouds proximal. The phenomena you claim are trumped by those I actually see.

You do not understand what you are actually seeing - because, you have been so successfully "trained" (as we all are/were) to believe that what you are seeing is a far-away sun "falling" over-and-beyond the horizon.

I know it is difficult for you to see it as it really is; however, what prevents you from seeing it is more a matter of your [deeply-entrenched] belief in what you have been taught than what your senses actually perceive.

You do not understand what you are actually seeing - because, you have been so successfully "trained" (as we all are/were) to believe that what you are seeing is a far-away sun "falling" over-and-beyond the horizon.

I know it is difficult for you to see it as it really is; however, what prevents you from seeing it is more a matter of your [deeply-entrenched] belief in what you have been taught than what your senses actually perceive.

I would encourage you to consider the profound arrogance of your post.