Please could someone advise the best method of finding the solar noon based on location?


The stuff on here has been helpful but I can't figure out what I should be finding out! LST sounds about right, but I'm not 100% sure.

  • 2
    $\begingroup$ Wolfram Alpha is perfect for these sorts of queries (if you don't want to calculate it yourself from scratch). Example: wolframalpha.com/input/?i=solar+noon+in+washington $\endgroup$
    – Moriarty
    Oct 27 '13 at 13:19
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    $\begingroup$ Maybe I should have said, the reason I want a formula is that i'm making a program that gets the users sunset and sunrise times and I want to incorporate solar noon times for better accuracy. $\endgroup$ Oct 27 '13 at 13:22
  • $\begingroup$ Just to clarify, are you looking for the local time that LST occurs? $\endgroup$
    – user8
    Oct 27 '13 at 19:34
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    $\begingroup$ This is a pretty handy source: answers.google.com/answers/threadview/id/782886.html. I think you latitude on the Earth's surface will only affect how high in altitude the sun gets at local solar noon. $\endgroup$
    – astromax
    Oct 27 '13 at 20:39
  • $\begingroup$ @astromax - good find, and yes, you are right about the latitude. The longitude is a key component in determining local solar time - as in both the link in the question and your link. $\endgroup$
    – user8
    Oct 28 '13 at 10:50

Taking solar noon as being the time when the sun is at its highest elevation (altitude) in the sky for a given day, then your assumption of the LST (local solar time) is correct, as it is stated in the website you linked as being:

Twelve noon local solar time (LST) is defined as when the sun is highest in the sky. Local time (LT) usually varies from LST because of the eccentricity of the Earth's orbit, and because of human adjustments such as time zones and daylight saving.

This is something I have, in part, programmed into an app for a separate project (quite unrelated to yours).

You would have to equate the precedent quantities first (Local Standard Time Meridian, Equation of Time and Time Correction factors) as they have done on the website you linked (as these are reliant on the observer's position and time of observation), but to determine at what time solar noon occurred, the final step needs to have local solar time (LST) set to 12:00 (solar noon).

A worked exampled is given within the first 7 pages/slides of Sunlight and its Properties II.


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