Sun dials need to be adjusted throughout the year to account for axial tilt. If you do not, you will get inaccurate times (as seen in your meme). Get you own sun dial and you will see for yourself.
“Solar time and clock time line up at noon on April 15, June 15, September 1 and December 24, which is why those days are recommended for setting a sundial. If you want your sundial to be as accurate as possible, reset your dial on each of those dates.”
This is something you can test yourself with a post. Mark the shadow of the post at noon once a week for a year. You WILL see the same shadow patterns that your meme is showing, 100%.
Sun dials DO in fact “point In drastically different directions through the 4 seasons.”
Congratulations, this is probably the best argument AGAINST the flat earth model I ever saw. Why would sun dials “point In drastically different directions through the 4 seasons” on a flat earth?
Analemma's disprove your claim. You can capture an annalema by taking a picture of the sun at one location, every 24 hours, for a whole year. The sun will produce a figure 8 pattern. This will cause the shadow on a sun dial to vary a miniscule amount through the seasons. This is not enough to throw off a sun dial for practical purposes. Ideally you would align the dial to somewhere in the middle of the annalemma.
In the globe demonstration above it looks like spring and fall would have the shadow cast at about a 45+ degree angle difference. Sun dials don't have to be adjusted once you set them up. Some ancient sundials haven't moved in thousands of years.
But you are right, sundials do not NEED to be adjusted seasonally… unless you want to accurately tell time with it seasonally. However they will remain accurate on a year to year basis without adjustment (like the ancient sundials you speak of).
“You can capture an annalema by taking a picture of the sun at one location, every 24 hours, for a whole year.”
If you do the same thing with the shadow of a post, or sundial, the same figure 8 shape will appear. The “fat” part of the figure 8 is not “minuscule” when it comes to telling time.
The noon shadow on a sundial varies and has a range of over 30 minutes throughout the year. Sundials are only accurate April 15, June 15, September 1 and December 24 (the exact middle of the analemma, and what most sundials are zeroed to).
You said sundials wont work on a globe because they would point in different directions seasonally. THEY DO, 100% fact.
Your meme also shows an exaggerated difference in “noon” shadows by not having the point centered on the globe. In the left picture, the point is set to the right of center. In the right picture, the point is set to the left of center. This will result in a more drastic angle. It is essentially comparing the 11 am-ish shadow to the 1 pm-ish shadow.
The light does appear to be centered. You can tell because the marker is oriented directly towards the camera on both pics. The reason the highlight is off the line you drew is because the camera (observer) is higher than the light (sun). The highlight would only be spot on if the light and the camera were in the exact same angle. The geometry isn't hard to comprehend. You really think you can correct that big of an angle difference with the shadow?
I told someone this in another post:
I have a public sundial that I look at down the street. All year long the thing is accurate to within 15 minutes or less. No one ever adjusts it because it's set in concrete. I would have to measure how many degrees off it is at maximum, but I would guess 1 or 2 degrees (angle of the shadow). I want to test out that globe simulation so I could get a rough estimate of how far off the shadow is between spring and fall, but if those pics are at all accurate, 45+ degrees off would equate to HOURS of error. It's not even close.
The light is on the OTHER side of the centerline. This will result in even MORE of an angle.
“accurate to within 15 minutes or less.”
15 minutes on either side is a 30 minute range, like I said. You need to “adjust” for that seasonally. The sundial does not have to be physically moved, the time needs adjustment. Can’t believe I need to spell that out.
“guess 1 or 2 degrees”
We do not need to guess, 30 minutes on a sundial is 20 degrees. Get a protractor and sundial and measure yourself. It is very funny you guessed 1-2, way WAY off.
To sum up, your 45 degree estimate is way too big. And your estimate of 1-2 degrees is way too small.
Sun dials need to be adjusted throughout the year to account for axial tilt. If you do not, you will get inaccurate times (as seen in your meme). Get you own sun dial and you will see for yourself.
“Solar time and clock time line up at noon on April 15, June 15, September 1 and December 24, which is why those days are recommended for setting a sundial. If you want your sundial to be as accurate as possible, reset your dial on each of those dates.”
This is something you can test yourself with a post. Mark the shadow of the post at noon once a week for a year. You WILL see the same shadow patterns that your meme is showing, 100%.
Sun dials DO in fact “point In drastically different directions through the 4 seasons.”
Congratulations, this is probably the best argument AGAINST the flat earth model I ever saw. Why would sun dials “point In drastically different directions through the 4 seasons” on a flat earth?
Source
https://www.myfrugalhome.com/set-your-sundial/#:~:text=Solar%20time%20and%20clock%20time,on%20each%20of%20those%20dates.
Analemma's disprove your claim. You can capture an annalema by taking a picture of the sun at one location, every 24 hours, for a whole year. The sun will produce a figure 8 pattern. This will cause the shadow on a sun dial to vary a miniscule amount through the seasons. This is not enough to throw off a sun dial for practical purposes. Ideally you would align the dial to somewhere in the middle of the annalemma.
In the globe demonstration above it looks like spring and fall would have the shadow cast at about a 45+ degree angle difference. Sun dials don't have to be adjusted once you set them up. Some ancient sundials haven't moved in thousands of years.
https://en.m.wikipedia.org/wiki/Analemma
In no way does analemma disprove my claim.
But you are right, sundials do not NEED to be adjusted seasonally… unless you want to accurately tell time with it seasonally. However they will remain accurate on a year to year basis without adjustment (like the ancient sundials you speak of).
“You can capture an annalema by taking a picture of the sun at one location, every 24 hours, for a whole year.”
If you do the same thing with the shadow of a post, or sundial, the same figure 8 shape will appear. The “fat” part of the figure 8 is not “minuscule” when it comes to telling time.
The noon shadow on a sundial varies and has a range of over 30 minutes throughout the year. Sundials are only accurate April 15, June 15, September 1 and December 24 (the exact middle of the analemma, and what most sundials are zeroed to).
You said sundials wont work on a globe because they would point in different directions seasonally. THEY DO, 100% fact.
Your meme also shows an exaggerated difference in “noon” shadows by not having the point centered on the globe. In the left picture, the point is set to the right of center. In the right picture, the point is set to the left of center. This will result in a more drastic angle. It is essentially comparing the 11 am-ish shadow to the 1 pm-ish shadow.
Here is a picture showing this:
https://gab.com/TheGreyGuy/posts/110703866648658230
I know how you people continuously move the goal post, so I am done. Have a good life.
The light does appear to be centered. You can tell because the marker is oriented directly towards the camera on both pics. The reason the highlight is off the line you drew is because the camera (observer) is higher than the light (sun). The highlight would only be spot on if the light and the camera were in the exact same angle. The geometry isn't hard to comprehend. You really think you can correct that big of an angle difference with the shadow?
I told someone this in another post: I have a public sundial that I look at down the street. All year long the thing is accurate to within 15 minutes or less. No one ever adjusts it because it's set in concrete. I would have to measure how many degrees off it is at maximum, but I would guess 1 or 2 degrees (angle of the shadow). I want to test out that globe simulation so I could get a rough estimate of how far off the shadow is between spring and fall, but if those pics are at all accurate, 45+ degrees off would equate to HOURS of error. It's not even close.
The light is on the OTHER side of the centerline. This will result in even MORE of an angle.
“accurate to within 15 minutes or less.”
15 minutes on either side is a 30 minute range, like I said. You need to “adjust” for that seasonally. The sundial does not have to be physically moved, the time needs adjustment. Can’t believe I need to spell that out.
“guess 1 or 2 degrees”
We do not need to guess, 30 minutes on a sundial is 20 degrees. Get a protractor and sundial and measure yourself. It is very funny you guessed 1-2, way WAY off.
To sum up, your 45 degree estimate is way too big. And your estimate of 1-2 degrees is way too small.