so why do ships disappear over the horizon?

Well explained...  8-)  I get what you're saying now.

Quote from: "CharlesJohnson"

Then why is it that when we stand on top of a 30 story building on the
seafront, we can see ships that aren't visible from the shoreline?

Surely climbing the 30 story building would only place more atmosphere
between myself and the ship on the horizon.

I've tried it, it works.

Lets not avoid my question.... you Flat Earthers are good at that,
I'm not letting this one slide.

Let's see how hard it will be to calculate the amount (?) of atmosphere in the line of vision.  I think I'm going to have to use a line integral, which hasn't happened in my head for five years.  

Anyone have a better idea than line integrals?

To be honest... if you want to accurately calculate that, I think line
integrals are the only way. The problem is, if you're going to account for
the minimal change in density, you might as well also take into
consideration that the path the light follows will not be straight, due to
refraction.

The easiest way to do this, would be to use the fact that the change in
density is miniscule over the height of a 30 story building. Because of this,
even if the entire path of the light from ship to building top were to pass
through the lowest possible density (density atop the building), this path
would still be longer than the other path from ship to observer on the shoreline.

To be honest... if you want to accurately calculate that, I think line
integrals are the only way. The problem is, if you're going to account for
the minimal change in density, you might as well also take into
consideration that the path the light follows will not be straight, due to
refraction.

But that will be hard!

The easiest way to do this, would be to use the fact that the change in
density is miniscule over the height of a 30 story building. Because of this,
even if the entire path of the light from ship to building top were to pass
through the lowest possible density (density atop the building), this path
would still be longer than the other path from ship to observer on the shoreline.

Wiki says the change in pressure is 9 Pa/m, but it can't be any where as linear as that.  Yeah, it's all negligible.  I'll drop it.

Its more than I thought it would be...

In any case... this would be pointless because if from the shore the
furthest we can see out is 8km (at a guess - I dont feel like calc it, and
I remember it being something around this value) If I was looking out to
that same 8km point from the top of a 100m building, the change in
distance would be 30cm  :lol: Or something stupid like that.

I should have seen this coming from the beginning of this argument  :roll:

So I guess what the original argument should have been is:

Why can I see more from the top of a high point, when in the flat earth
model, the distance to the horizon is essentially the same as it would
be if I was looking out from the ground?

Yeah yeah I know... The path the light follows to a higher point, passes
through areas where the atmosphere is less dense.