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Offline Bobby Shafto

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Re: More on "13 Miles: 60 ft NOT Hidden".
« Reply #100 on: December 23, 2018, 07:44:26 AM »
So we agree on the flat results, but not on the sphere. Not sure why, but I'll attach my spreadsheet so you can have a look...

Looks to me like your spreadsheet doesn't factor atmospheric refraction.  If you apply a standard adjustment of 7/6*r for the radius value, or 4619 miles instead of 3958, looks to me like you get outputs closer to mine.

If you are applying refraction already, I didn't find it; but if so I don't know why the difference then.

Re: More on "13 Miles: 60 ft NOT Hidden".
« Reply #101 on: December 23, 2018, 09:36:07 AM »
That'll be it. :)

With refraction, I get: 0.0333°, 0.0520°, and 0.0870° - same.

Cheers Bobby, that's actually really useful for something else. :)
If you've proven yourself immune to logic and incapable of reasonable debate, please understand that I won't be paying you much heed (this means you, Baby Thork, Sandokhan, Tom Bishop, and Totallackey).

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Offline Bobby Shafto

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Re: More on "13 Miles: 60 ft NOT Hidden".
« Reply #102 on: December 23, 2018, 05:29:37 PM »
That'll be it. :)

With refraction, I get: 0.0333°, 0.0520°, and 0.0870° - same.

Cheers Bobby, that's actually really useful for something else. :)

Great. And for comparison, here is how those two geometries might compare visually:



I've tried to work this out in other views of distant landmarks before too, like my viewing of Mt Helix and Viejas from Cabrillo Point, JTolens' IR pictures of Mount Jacinto from Malibu, some views of Hawk Hill in the background of Brighton as viewed from Worthing...the vertical angles are always depressed. I didn't go looking for it here since I was just trying to experiment with using the mirror, but it works out again.

It's a little more involved than trying to assess a horizon being at eye level, and a little harder to show than images portraying "sunken ship effect," but it's the same concept.

I'm not a surveyor, of course, and these angles still have large angles of incidence meaning refraction by the air is still a factor. But so far as I've found, the analysis of vertical angles consistently favors globe topology vice flat.

But onto the next step. Next opportunity with good enough visibility, I'll be attempting to duplicate the F.R.E.E. group's mirror reflection sighting across the span from La Jolla to Encinitas (about 12 miles),  to Leucadia (about 15 miles) and to Carlsbad (20 miles).

Re: More on "13 Miles: 60 ft NOT Hidden".
« Reply #103 on: December 24, 2018, 01:35:44 AM »
Let me know when you can see it at the same level, meaning lower the camera a half foot off the ground and record it.

Re: More on "13 Miles: 60 ft NOT Hidden".
« Reply #104 on: December 24, 2018, 01:49:04 AM »
Here try this one it's easier and dont video it because I dont want you to be embarrassed publicly about believing the earth is flat.
Get to altimeters goto the shore in Malibu and Catalina in line of sight with each other.
Then using the altimeters place the mirror and a laser at the same height not off the ground from each other but via the same height the two altimeters read the same and see if you can get a reflection.

Re: More on "13 Miles: 60 ft NOT Hidden".
« Reply #105 on: December 24, 2018, 01:57:33 AM »
If you look at the video the camera and people aren't at sea level, sea level would be touching the water. It is well above the sea level as is the mirror she is not at the water either.
Please learn how to do a scientific experiment and not just some mileninal political science majors attempt at one.

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Offline Bobby Shafto

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Re: More on "13 Miles: 60 ft NOT Hidden".
« Reply #106 on: December 24, 2018, 02:18:49 AM »
If you look at the video the camera and people aren't at sea level, sea level would be touching the water. It is well above the sea level as is the mirror she is not at the water either.
Please learn how to do a scientific experiment and not just some mileninal political science majors attempt at one.
Allow me to play the flat earth advocate since the folks who performed this demo do not participate on this forum and won't see your insult.

The heights at which the mirror and the camera were positioned don't need to be at 0' above the level of the water. Even if both were 5' above the water's surface (which is what I think is a reasonable estimate), the light path from the mirror should not have been detectable by the camera lens. With standard refraction, there should still have been 63-69 ft hidden behind the globe earth horizon, meaning any camera height less than that should not detect the mirror flash. With moderate levels of refraction, that hidden value drops to 44-62 ft, which is still more than a camera placed at 5' above the water surface on the far shore should be able to capture. Bump to the refraction up to  very strong levels, and that still leaves 26-43' hidden behind the curve of the earth.

A surface-level shallow-height temperature inversion could form a light-trapping duct that could possible cause the light to follow the curve of a globe earth, but there aren't the secondary visual artifacts that such a condition was present. So even in strong looming conditions, I'd still expect the camera to need to be at least around 20' high to have successfully detected that mirror reflection, even if under the most advantageous of atmospheric conditions, if we are to trust that the earth is a globe of radius 3959 miles.

Re: More on "13 Miles: 60 ft NOT Hidden".
« Reply #107 on: December 27, 2018, 10:45:39 PM »
Some good analysis here



Not entirely sure I understand the explanation for the flashes but the point about the lower part of the building being hidden is pretty solid
If you are making your claim without evidence then we can discard it without evidence.

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Offline Bobby Shafto

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Re: More on "13 Miles: 60 ft NOT Hidden".
« Reply #108 on: December 29, 2018, 11:53:30 PM »
1st look at trying to replicate OP video experiment.

Will be assembling footage, but this was the lowest elevation we could successfully  get today.

Distance 12.9 miles.

Camera at ~25' in La Jolla



Mirror at ~20-25' in Encinitas




Right at the "fold" line of inferior mirage:



More later.

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Offline stack

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Re: More on "13 Miles: 60 ft NOT Hidden".
« Reply #109 on: December 31, 2018, 08:54:03 AM »
According to Bilsin's the mirror should be 6' below the fold, hidden. The mirror is what, 7" in diameter? Looks like feet, maybe yards. So much distortion. Yellow marks where the mirror is/1 frame of flash, red what I think is the distorted landmark.


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Offline Bobby Shafto

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Re: More on "13 Miles: 60 ft NOT Hidden".
« Reply #110 on: December 31, 2018, 07:32:59 PM »
The inferior mirage "fold" is not a distinct line. Not saying that's what you said, but just pointing out that it IS distorting. It stretches, and you see that in the image.

The reflected light in that particular frame grab is from a 7" diameter circular mirror. We also used a larger one (16" diameter I think?) and a smaller one: a 3"x5" mil std survival mirror. All 3 were visible when flashed from 70', but we just went with the 7" one for the rest of test down the stairs to the beach.

I think the flash to the observer is always going to be larger than the mirror itself, mirage or no mirage. The beam will spread and it's basically the brightness of the sun so it'll flare. That low an angle across the surface of water, and I image moisture and aerosols will contributing to the blooming of the light.

I haven't cracked the code on when to expect inferior mirage or not. Some days it's absent. More often than not, it's there though. Sometimes strong like on this day. Other days weak. But looking at air temp, sea temp, time of day doesn't afford me anything predictive.

What I want to know is what is behind the inverted image of the mirage? If you could erase it, would you see more of the distant land below that line where the mirror flash became obscured? Or you see the sea rise and reveal itself to be what is obscuring the light? I think I understand the answer, but I don't know for sure. I'll just have to keep doing this, hoping for another clear day when there is no distortion by mirage.

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Offline Bobby Shafto

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Re: More on "13 Miles: 60 ft NOT Hidden".
« Reply #111 on: January 08, 2019, 04:15:55 PM »

I haven't cracked the code on when to expect inferior mirage or not. Some days it's absent. More often than not, it's there though. Sometimes strong like on this day. Other days weak. But looking at air temp, sea temp, time of day doesn't afford me anything predictive.

What I want to know is what is behind the inverted image of the mirage? If you could erase it, would you see more of the distant land below that line where the mirror flash became obscured? Or you see the sea rise and reveal itself to be what is obscuring the light? I think I understand the answer, but I don't know for sure. I'll just have to keep doing this, hoping for another clear day when there is no distortion by mirage.

Not what I expected.





Red-outlined arrow is where the lowest point the mirror could be seen during mirage conditions. The (near) absence of inferior mirage reveals about 5-7' more of the stairs and maybe the tip of the guard tower roof.  This is a screen capture from a video I shot yesterday evening about 30-45 minutes before sunset. Tide was just turning on a -0.6 low.