[Curiosity File]

About 800 miles apart, from the top of each <(Washington Monument to Gateway Arch St Louis), what can you see and what can't you see of each structure in relation and comparison to FE vs RE? And Why?
Then a shorter distance from the Washington Monument to the WTC New York or any high raise in Ney York

Here's some heights to start with.
https://www.nps.gov/jeff/planyourvisit/arch-height.htm

[totallackey]

About 800 miles apart, from the top of each <(Washington Monument to Gateway Arch St Louis), what can you see and what can't you see of each structure in relation and comparison to FE vs RE? And Why?
Then a shorter distance from the Washington Monument to the WTC New York or any high raise in Ney York

Here's some heights to start with.
https://www.nps.gov/jeff/planyourvisit/arch-height.htm

Earth's shape has nothing to do with your query.

The farthest one could see due to haze and other such issues is around 300 km.

[Curiosity File]

About 800 miles apart, from the top of each <(Washington Monument to Gateway Arch St Louis), what can you see and what can't you see of each structure in relation and comparison to FE vs RE? And Why?
Then a shorter distance from the Washington Monument to the WTC New York or any high raise in Ney York

Here's some heights to start with.
https://www.nps.gov/jeff/planyourvisit/arch-height.htm

Earth's shape has nothing to do with your query.

The farthest one could see due to haze and other such issues is around 300 km.

FET claims the moon is 4,828 km from the Earth. RE technology measures the Moon to be 386,242 km from the Earth.
The Sun is blocked by the Moon in eclipse.
Point being you can see much farther than 300 km unless solid objects obscure line of sight.
Sure weather conditions can limit distance of sight but lets say, hypothetical, it's a clear day and you drop a coin in one of the powerful binoculars or telescopes that are available on the the structures mentioned, or you bring your own.

But totallakey, you bring up the question, why is or sight limited to 300 km when looking out across the Earth?       

[totallackey]

About 800 miles apart, from the top of each <(Washington Monument to Gateway Arch St Louis), what can you see and what can't you see of each structure in relation and comparison to FE vs RE? And Why?
Then a shorter distance from the Washington Monument to the WTC New York or any high raise in Ney York

Here's some heights to start with.
https://www.nps.gov/jeff/planyourvisit/arch-height.htm

Earth's shape has nothing to do with your query.

The farthest one could see due to haze and other such issues is around 300 km.

FET claims the moon is 4,828 km from the Earth. RE technology measures the Moon to be 386,242 km from the Earth.
The Sun is blocked by the Moon in eclipse.
Point being you can see much farther than 300 km unless solid objects obscure line of sight.
Sure weather conditions can limit distance of sight but lets say, hypothetical, it's a clear day and you drop a coin in one of the powerful binoculars or telescopes that are available on the the structures mentioned, or you bring your own.

But totallakey, you bring up the question, why is or sight limited to 300 km when looking out across the Earth?     

In the instances you bring up, the objects being viewed occupy a position well above the plain of the flat earth.

Objects such as mountains, tall buildings, etc., are not that high above the flat plain.

Given the air in the atmoplane is denser at low altitude, there exists objects that will block the view and even air clarity is affected.

Even RET apologists acknowledge: "On the top of Mt Everest, you could theoretically see for 339 kilometres (211 miles), but in practice cloud gets in the way."

[Curiosity File]

About 800 miles apart, from the top of each <(Washington Monument to Gateway Arch St Louis), what can you see and what can't you see of each structure in relation and comparison to FE vs RE? And Why?
Then a shorter distance from the Washington Monument to the WTC New York or any high raise in Ney York

Here's some heights to start with.
https://www.nps.gov/jeff/planyourvisit/arch-height.htm

Earth's shape has nothing to do with your query.

The farthest one could see due to haze and other such issues is around 300 km.

FET claims the moon is 4,828 km from the Earth. RE technology measures the Moon to be 386,242 km from the Earth.
The Sun is blocked by the Moon in eclipse.
Point being you can see much farther than 300 km unless solid objects obscure line of sight.
Sure weather conditions can limit distance of sight but lets say, hypothetical, it's a clear day and you drop a coin in one of the powerful binoculars or telescopes that are available on the the structures mentioned, or you bring your own.

But totallakey, you bring up the question, why is or sight limited to 300 km when looking out across the Earth?     

In the instances you bring up, the objects being viewed occupy a position well above the plain of the flat earth.

Objects such as mountains, tall buildings, etc., are not that high above the flat plain.

Given the air in the atmoplane is denser at low altitude, there exists objects that will block the view and even air clarity is affected.

Even RET apologists acknowledge: "On the top of Mt Everest, you could theoretically see for 339 kilometres (211 miles), but in practice cloud gets in the way."

Why can you only see 211 miles on a clear day from top Mt Everest?

[rabinoz]

Even RET apologists acknowledge: "On the top of Mt Everest, you could theoretically see for 339 kilometres (211 miles), but in practice cloud gets in the way."

Why can you only see 211 miles on a clear day from top Mt Everest?

Because of  the Scattering of Light. in the atmosphere.
The 339 kilometres that totallackey gives is quite correct and is an upper limit for perfectly clear air at sea-level.
The visibility distance near sea-level is usually much less due to fine particles in the air though it can be more at higher altitudes as in:
          Beyond Horizons, Pic de Finestrelles – Pic Gaspard (Ecrins) | 443 km. AUGUST 3, 2016 ~ MARK BRET.

[Curiosity File]

Even RET apologists acknowledge: "On the top of Mt Everest, you could theoretically see for 339 kilometres (211 miles), but in practice cloud gets in the way."

Why can you only see 211 miles on a clear day from top Mt Everest?

Because of  the Scattering of Light. in the atmosphere.
The 339 kilometres that totallackey gives is quite correct and is an upper limit for perfectly clear air at sea-level.
The visibility distance near sea-level is usually much less due to fine particles in the air though it can be more at higher altitudes as in:
          Beyond Horizons, Pic de Finestrelles – Pic Gaspard (Ecrins) | 443 km. AUGUST 3, 2016 ~ MARK BRET.

So why can we see the moon through haze and smog etc. on the horizon from one end of the earth to the other plus it's 3,000 mile flat earth distance or 239k miles RE? But all this evades the point/the question, which is, and we'll get right to the point without playing anymore circle jerk games.

What obstructs your vision from seeing an object more than 10 miles away on a clear calm day on the ocean from say 6 feet above see level, with or without a telescope? 

[rabinoz]

So why can we see the moon through haze and smog etc. on the horizon from one end of the earth to the other plus it's 3,000 mile flat earth distance

Don't ask me about what might happen on a flat earth - that's not my problem.

or 239k miles RE?

On the Globe, when the moon is overhead the effective thickness of the atmosphere is only about 9 km and
when on the horizon (if my memory serves me correctly) the effective thickness of the atmosphere is roughly 200 km.

If the air is "very dirty" the moon cannot be seen when close to the horizon but when the atmosphere is clear the moon can be quite sharp though less bright and redder than when overhead.

But all this evades the point/the question, which is, and we'll get right to the point without playing anymore circle jerk games.

What obstructs your vision from seeing an object more than 10 miles away on a clear calm day on the ocean from say 6 feet above see level, with or without a telescope?

Now that is also my question - the $64,000 one !