[Tumeni]

And as far as the ship video is concerned, how large a wake do you propose a cruise ship would make?

It will only make a wake to the rear of the ship, with a bow wave spreading out from the sides, always behind the bow.

So, in the video above, where one ship goes away, the other approaches the camera, the second one will have no wake between it and the camera or observer.

Let's do the long hotel corridor, then;

The corridor is 12 ft high from floor to ceiling. You, the observer, are 6ft 4ins tall, so your eyes are at exactly 6 feet above the floor, and 6 ft below the ceiling.

Let's ignore what's happening in the far distance for the moment. Yes, the ceiling, floor and walls APPEAR to converge to a point, but we all know the corridor does not get narrower or shallower.

Do you agree that the floor is, at all points, below your eye level? Eye level is parallel to the floor, at 6 ft above it, so you must be looking downward when you look at the floor, right?

Do you agree that if you look at a point on the floor some 20 ft away, your line of sight to that point, from 6 ft above the floor, passes through a level of 5 ft, 4, 3, 2, 1, 6 inches, down to zero?

It's a straight line of sight, isn't it? No refraction, fog, or other atmospherics to distort it? It doesn't curve upward, then back down to reach the floor. You're looking straight at the floor. Right?

[Action80]

Why does the ceiling in the hallway appear to start merging with the floor at a distance?

It doesn't. I mean, if you were in a long enough corridor then I guess at some distance you might not be able to make out the ceiling from the floor.

ITT - AATW writes the classic, "It doesn't, but it does."

But you could zoom in with a decent camera and see clearly the gap between them.

And then further past the original point of merging, a new merging would occur.

But the horizon is a clearly defined line on a clear day and remains so no matter how much you zoom in.

All things appear to be clearly defined on a clear day and this has nothing to do with the shape of the earth.

[Action80]

The horizon is as far as you can see.

It is there, just the same as it would be there if I was in a known to be perfectly level, hallway say of 10 miles distance.

If it is as far as you can see, why can we see objects behind it? Why can I see the horizon, for example, in front of the lower half of a distant ship? Or the sun?

Maybe the words, "where two levels meet," would be satisfatory.

[SteelyBob]

Maybe the words, "where two levels meet," would be satisfatory.

No, they would not be satisfactory at all. They would not because they are, firstly, wholly unsatisfactory as a definition or explanation of what the horizon is. Furthermore, they don't stand up to any kind of scrutiny. What is a 'level'? What two 'levels' are we talking about, in the context of a seascape? The sea and the sky? Since when is the sky a 'level'? And if it's where they meet, why is the horizon so close, in relative terms, and what is going on beyond it? Why does it vary in distance with the elevation of the observer?

[AATW]

But the horizon is a clearly defined line on a clear day and remains so no matter how much you zoom in.

All things appear to be clearly defined on a clear day and this has nothing to do with the shape of the earth.

It kinda does. A sharp line is usually the edge of something. So in this diagram.
The distant coloured bar would not be visible from a low altitude. From higher up the top portion of it would be visible. From even higher you'd see more.
And the horizon - marked by the smaller black lines - is further away as you ascend.



That's what we observe and it can be explained by a globe earth. At the bottom I've shown the FE scenario. Why would there be a sharp horizon line and why would you only see the top of distant objects? You said the horizon is "as far as you can see". But that can't be true because you can clearly see things beyond the horizon. You just can't see the bottom of them. Why not? The bottom is as far away as the top.

[stack]

And as far as the ship video is concerned, how large a wake do you propose a cruise ship would make?

Apparently, not that big...

[BillO]

The wave in Alaska (Lituya Bay, I believe) was over 1700 feet high.
I am not making anything up.

You are.

You are misinterpreting the event.  Read the analysis.   The actual swell in the water (the wave) was about 100 feet however it's momentum drove it (run-up) over 1,700 up the head of the bay.  If there was nothing there to stop it it would never have reached over 100 feet.  It was also an unusual wave that was not traveling at the normal speed of waves in water for that depth.  It was in effect a shock wave that, had it propagated out to open sea, would have slowed dramatically.

[SimonC]

And as far as the ship video is concerned, how large a wake do you propose a cruise ship would make?

Apparently, not that big...

Was the curvature put in for good measure or just a wide angle lens proving that these days the camera always lies? 

[stack]

And as far as the ship video is concerned, how large a wake do you propose a cruise ship would make?

Apparently, not that big...

Was the curvature put in for good measure or just a wide angle lens proving that these days the camera always lies? 

No. It's a fish-eye lens. And the video has nothing to do with curvature. The intent of the video, which you have completely missed, is to show that cruise ship wakes aren't monstrously large as suggested by another poster. You might want to actually read the posts and understand the context before launching into something completely irrelevant.

[SimonC]

And as far as the ship video is concerned, how large a wake do you propose a cruise ship would make?

Apparently, not that big...

Was the curvature put in for good measure or just a wide angle lens proving that these days the camera always lies? 

No. It's a fish-eye lens. And the video has nothing to do with curvature. The intent of the video, which you have completely missed, is to show that cruise ship wakes aren't monstrously large as suggested by another poster. You might want to actually read the posts and understand the context before launching into something completely irrelevant.

I think if you reread my post you will see that it was an incidental comment and coincidentally it is relevant as the topic was concerned with curvature of the earth. And fish eye lenses don't help with proving that theory. I completely accept you were videoing the wake and found it humorous that a false curvature was incorporated into the images. 

[Tron]

Technically, if the earth were round, wouldn't the horizon take a spherical shape?

[SteelyBob]

Technically, if the earth were round, wouldn't the horizon take a spherical shape?

No. It would be appear level, because the horizon on a sphere, to an observer, is a circle whose radius varies with the observer’s height above the surface. The higher you are, the bigger the circle, but it’s the same in every direction. So no, it wouldn’t appear to curve.

[AATW]

If the earth were flat then why would there be a horizon at all? Why would there be a sharp line beyond which you can't see?
It's not visibility, you can see the top of ships and landmarks beyond the horizon.

[Tron]

If you watched three sail boats sailing away and slowly disappearing because of the earths curvature, then wouldn't you need to assume that the tops of those ships wouldn't be parallel to one another? 



Sorry to hijack this post, but it is similar.

[SteelyBob]

If you watched three sail boats sailing away and slowly disappearing because of the earths curvature, then wouldn't you need to assume that the tops of those ships wouldn't be parallel to one another? 



Sorry to hijack this post, but it is similar.

Great question.

Yes…sort of. For a typical situation out at sea, for example, the horizon is usually single digit or low double digit numbers of miles away - it depends on your elevation above the water, and on the atmospheric conditions. For those kind of distances, the difference in angle between the masts wouldn’t be noticeable. If you elevated yourself tens of miles above the surface, then you would notice a difference, not just in the left / right angle of the masts as per your diagram, but also the ‘dip’ as the ships are tilting forwards away from you.

[stack]

And as far as the ship video is concerned, how large a wake do you propose a cruise ship would make?

Apparently, not that big...

Was the curvature put in for good measure or just a wide angle lens proving that these days the camera always lies? 

No. It's a fish-eye lens. And the video has nothing to do with curvature. The intent of the video, which you have completely missed, is to show that cruise ship wakes aren't monstrously large as suggested by another poster. You might want to actually read the posts and understand the context before launching into something completely irrelevant.

I think if you reread my post you will see that it was an incidental comment and coincidentally it is relevant as the topic was concerned with curvature of the earth. And fish eye lenses don't help with proving that theory. I completely accept you were videoing the wake and found it humorous that a false curvature was incorporated into the images.

You're still missing the point and strawmanning your way though this. The video was never intended to visually represent the curvature of the earth. It simply was showing the much smaller size of the wake from a cruise ship than previously asserted by another poster. That's all.

Just to satisfy your strange need, here's another one:



Flat horizon, tiny wake. Feel better now?

[SimonC]

If you watched three sail boats sailing away and slowly disappearing because of the earths curvature, then wouldn't you need to assume that the tops of those ships wouldn't be parallel to one another? 



Sorry to hijack this post, but it is similar.

Great question.

Yes…sort of. For a typical situation out at sea, for example, the horizon is usually single digit or low double digit numbers of miles away - it depends on your elevation above the water, and on the atmospheric conditions. For those kind of distances, the difference in angle between the masts wouldn’t be noticeable. If you elevated yourself tens of miles above the surface, then you would notice a difference, not just in the left / right angle of the masts as per your diagram, but also the ‘dip’ as the ships are tilting forwards away from you.

In reality though sailing boats bob up and down and tilt from side to side. Unless the sea was a flat calm (millpond-like) and there was a Force Zero wind then it would be impossible to prove.

[SimonC]

And as far as the ship video is concerned, how large a wake do you propose a cruise ship would make?

Apparently, not that big...

Was the curvature put in for good measure or just a wide angle lens proving that these days the camera always lies? 

No. It's a fish-eye lens. And the video has nothing to do with curvature. The intent of the video, which you have completely missed, is to show that cruise ship wakes aren't monstrously large as suggested by another poster. You might want to actually read the posts and understand the context before launching into something completely irrelevant.

I think if you reread my post you will see that it was an incidental comment and coincidentally it is relevant as the topic was concerned with curvature of the earth. And fish eye lenses don't help with proving that theory. I completely accept you were videoing the wake and found it humorous that a false curvature was incorporated into the images.

You're still missing the point and strawmanning your way though this. The video was never intended to visually represent the curvature of the earth. It simply was showing the much smaller size of the wake from a cruise ship than previously asserted by another poster. That's all.

Just to satisfy your strange need, here's another one:



Flat horizon, tiny wake. Feel better now?

I never said anything like that. It was an incidental almost rhetorical question. And I am still tickled as the use of fish-eye lenses for whatever reason on a FE site have the propensity to cause the person viewing the resultant photos (depicting curvature of the earth) to subconciously have an image of a global earth imprinted on their brain.
That's all. I apologise if it didn't appear that way. And I also apologise to the Moderators if it was wrong to inject a little bit of humour into a topic.

[SimonC]

Technically, if the earth were round, wouldn't the horizon take a spherical shape?

Only if you were 30 - 50 miles above its surface. At ground level it would be a straight line.

[Tron]

So if we can detect curvature only a few miles out to sea, then shouldn't we be able to detect curvature accross the sea?   

I happen to believe that the earth starts to appear spherical from the sky, because of atmospheric refraction (the bending of images and light, etc)... 

Using the method of measuring two or three objects accross a certain distance from another, minimizes the same problems you get with measuring one object at a distance (on sea) - wind, ocean swell, and local refraction phenomena...  Because you can get an average of how high each "ship" is relative to one another, how verticle there masts are and the angles they point away from one another...   Doing this experiment on land with a few buildings or flag poles may also work.