[Morgenstund]

On a clear day we can see roughly 20 km through the atmosphere. The light coming from objects further away is diffracted and turns everything into a blue-green haze. You notice it when you approach a mountain range from the distance. First you see a faint, shimmering, gray outline of the mountain. Slowly the features become clear. The mountain doesn't suddenly pop into view. If the FE argument is that the horizon, the line formed between the surface of the Earth and the atmosphere, appears where our range of vision ends, then we should also see the same phenomenon on a foggy day with very reduced visibility, or whilst diving under water. But we don't. We actually get the haze I predict would be seen on a surface that extends beyond our range of vision. The conclusion is that the horizon is an edge that appears only on a curved surface.
If anybody feel I have strawman'ed FE arguments, please explain what the horizon is and how it can be seen on a flat Earth.

[Morgenstund]

I have used the image without permission, but I hope AllAroundTheWorld will forgive me. It illustrates my point perfectly.
On a GE (top image) the observer will see only atmosphere above the red line of sight. Below he will see the ground. That is how the horizon is 'created'.
On a FE (bottom image) the observer will see the ground both above and below the red line of sight, as far as the range of vision allows. There would be no horizon like we observe on the GE. Only if we could se the actual edge of a FE would the be a horizon visible. (But as I understand it, 'They' (R) won't allow anybody close to that edge because of reasons.)

[Macarios]

On a clear day we can see roughly 20 km through the atmosphere.

On a clear day we can see a little farther.

From Valparaiso, Chile you can see Aconcagua (upper part), 160 km away.
Why is horizon much closer than that?
(Unless you climb 2000 meters high.)

[Morgenstund]

On a clear day we can see roughly 20 km through the atmosphere.

On a clear day we can see a little farther.

From Valparaiso, Chile you can see Aconcagua (upper part), 160 km away.
Why is horizon much closer than that?
(Unless you climb 2000 meters high.)

Perspective... I mean density... dammit. Could it be Universal acceleration? I don't know. All I know is that it is not the surface curving away in all directions. It is density, right?

[AATW]

Fine about the image. I used it originally to demonstrate why the horizon dips at a measurable angle and why that angle increases with altitude.
I’ve seen some suggestion that the horizon would be the same on a flat earth but I’m not sure about this. Why would you get such a sharp line? Nothing other than environmental conditions stops you seeing further so wouldn’t it just fade out more gradually?

[Morgenstund]

Fine about the image. I used it originally to demonstrate why the horizon dips at a measurable angle and why that angle increases with altitude.
I’ve seen some suggestion that the horizon would be the same on a flat earth but I’m not sure about this. Why would you get such a sharp line? Nothing other than environmental conditions stops you seeing further so wouldn’t it just fade out more gradually?

Thanks for playing along. I believe I have a pretty air tight argument for why there cannot be a horizon on a FE. I'm the new guy on the block, but I'm already getting the feeling that no FE believer will address any of the most obvious arguments against FE. Am I right?