Re^2: [OT] Astronomical puzzling about daylight hours at different latitudes

Thanks Tom for your detailed reply!

I want to thanks also other monks for their replies and yes: it was dumb from my part to forget the very basic definition of equinox.. but as always asking here is a pure pleasure because you have chances to get not only the correct answer but, more important, a lot panorama behind and sweeties to feed your brain.

*PS* incidentally I discovered Win32API::File::Time where Tom thanks dada and that the company they seem to work for produced the black and white film used in Eatalian neorealism movies as well all Totò's and Fellini's ones. Not all chemistry comes to hurt :)

There are no rules, there are no thumbs..
Reinvent the wheel, then learn The Wheel; may be one day you reinvent one of THE WHEELS.

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Re^3: [OT] Astronomical puzzling about daylight hours at different latitudes by cavac (Prior) on Sep 06, 2024 at 07:28 UTC
And don't forget, the length of a solar day changes over time, mostly due to redistribution of mass: liquid core, tectonic plate movement, tides (thanks, moon!), weather moving huge quantities of water, filling the Three Gorges Dam, and other stuff. That's why we have occasional leap seconds. Oh, and the place where you are is also moving around, thanks again to tectonic plate movement. Some places on earth only move millimeters/century. Others, like locations near the San Adreas fault can move at a nippy 5-7 centimeters per year (and presumably much faster when the next big earthquake hits, but in that case equinoxes might be the least of your problems). So if you need a very precise forecast, you may be out of luck. (If you need the to measure the day cycle to nano-second precission, you should also include air density, local gravity and your own speed to account for most relativistic effects). PerlMonks XP is useless? Not anymore: XPD - Do more with your PerlMonks XP Also check out my sisters artwork and my weekly webcomics	[reply]

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Re^3: [OT] Astronomical puzzling about daylight hours at different latitudes
by cavac (Prior) on Sep 06, 2024 at 07:28 UTC

And don't forget, the length of a solar day changes over time, mostly due to redistribution of mass: liquid core, tectonic plate movement, tides (thanks, moon!), weather moving huge quantities of water, filling the Three Gorges Dam, and other stuff. That's why we have occasional leap seconds.

Oh, and the place where you are is also moving around, thanks again to tectonic plate movement. Some places on earth only move millimeters/century. Others, like locations near the San Adreas fault can move at a nippy 5-7 centimeters per year (and presumably much faster when the next big earthquake hits, but in that case equinoxes might be the least of your problems).

So if you need a very precise forecast, you may be out of luck. (If you need the to measure the day cycle to nano-second precission, you should also include air density, local gravity and your own speed to account for most relativistic effects).

PerlMonks XP is useless? Not anymore: XPD - Do more with your PerlMonks XP
Also check out my sisters artwork and my weekly webcomics

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