Wolfram Alpha computes H as being equal to about 1400 feet. Thus, and unsurprisingly, this suggests that the target object would have to be much, much taller than the CN tower itself on a round Earth.

You forget that the 100 mile visibility claim is for ideal conditions. Those ideal conditions could include any of several atmospheric refraction phenomena that cause objects that would normally be blocked by the horizon to be visible. This is why I generally consider such convexity experiments to be largely inconclusive.

So the 100 mile visibility is only possible if conditions magically make the Earth look exactly as if it were flat, even though it's obviously round in reality. It's funny how often globularism falls back on that excuse.

I'd be interested in calculating whether or not even RE says it's possible for that much refraction to occur, but I honestly wouldn't know where to start.

That's how far the horizon is, not how far you can see.

I agree. Since the earth is flat, the distance to the horizon is irrelevant.

However, let's continue on with the delusion that globularism is a possible scenario here. In order to see something from the top of the CN tower, the distance to the horizon from the top of the target object plus the distance to the horizon from the top of the CN tower must be greater than or equal to the distance between the objects.

H_{1} + H_{2} >= D

We already have H_{1}, which Pongo calculated to be 45.65 miles. Since we're talking about a target object 100 miles away, the distance to the horizon from the target object is (generously) 54 miles (241,000 feet).

Let's reverse Pongo's equation to find how high this theoretical object would have to be.

241,000 = 20903520*ARCOS(20903520/(20903250+H))

Wolfram Alpha computes H as being equal to about 1400 feet. Thus, and unsurprisingly, this suggests that the target object would have to be much, much taller than the CN tower itself on a round Earth.

Congratulations to FEers on correcting two errors explained by REers' critiques of this sophomoric, failed proof. I'm happy to see that Pongo and revised his proof to use the altitude, not the height above CN Tower's foundation, of the observer. That took only 5 pages to correct one error.

Now I see that you've decided to correct, though snidely, Pongo's error when he failed to consider that the formula Pongo used provides the distance to the horizon (inaccurately), not the distance the observer can see. Congratulations on that, though it took 5 pages too.

Now let's review the remaining errors in the FEer failed proof:

1) The altitude of the surface of Lake Ontario, not just the radius of the RE, should be used.

2) The result, once you correct for the above error, is not the height of the target, as you claim. It's the altitude. Pongo understands that on the Tower side now. Now you need to consider it of the target side.

Once you fix the remaining errors, do stop back. Thank you for trying harder.

The 'failures' you incessantly refer (and honestly, You complain that I'm being snide?) to are actually simplifications, which are acceptable because a few dozen feet here or there don't really matter much when we're talking about thousands of feet. We're assuming a spherical cow, so to speak, because the true shape of the quadruped is a bit irrelevant. However, I'll sink to your level and address them anyway.

Pongo did use the altitude of Lake Ontario. He added that (inconsequential) value into his equation like, 2 pages ago or something. Anyway, so it's actually an 'altitude' of 1400 feet instead of a 'height' of 1400 feet. So what? It's still taller than the CN tower itself, even including the height above sea level. And believe it or not, I checked out the altitude of the Niagara Escarpment (since we're talking about Niagara) when I did the math. The exact altitude varied a lot and could be anywhere from 40 feet above sea level to 700 feet above sea level in a small area. Regardless, the building seen from the CN tower would need to be between 1400 and 700 feet tall, which would necessarily put it on the list of the tallest buildings in the US on Wikipedia. However, there are no such buildings in the area.

In conclusion, you cannot see 100 miles from the CN tower unless there's some magical RE refraction going on or the Earth is flat. Take your pick.