Lahaina Noon phenomenon - photo

Lahaina Noon phenomenon.

Lahaina Noon, also known as a zero shadow day, is a semi-annual tropical solar phenomenon when the Sun culminates at the zenith at solar noon, passing directly overhead (above the subsolar point).[1] As a result, the sun's rays will fall exactly vertical relative to an object on the ground and cast no observable shadow. - Wikipedia

https://diqn32j8nouaz.cloudfront.net...n_fullsize.jpg


Previously:

https://www.homemadetools.net/forum/...497#post222717
https://www.homemadetools.net/forum/...210#post195837
https://www.homemadetools.net/forum/...292#post192261
https://www.homemadetools.net/forum/...433#post215439
https://www.homemadetools.net/forum/...2932#post97558

That level is not plumb - look at the bottom vial

Makes it even more interesting not being plumb.

Quote:

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Originally Posted by Ralphxyz

Makes it even more interesting not being plumb.

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It is plumb !

When this coincidence of alignment of sun and earth position occurs, the sun's rays are exactly parallel to the radius vector from the center of the earth to that spot on the surface of the earth. Gravity acts along that radius so, if a tall object casts only a shadow directly below it, it must be aligned with that radius vector, which means it's perfectly vertical. If the bubble on the level doesn't indicate vertical, it needs to be recalibrated.