Developing formula for Hours of Sunshine

We developers can discuss this here instead of taking over the Feature Request.

(I asked Dan to move our developer posts from the Feature Requets topic to here)


21 posts were merged into an existing topic: Hours of sunshine

Let us decide on a good formula.

This is NO sunshine.


on monday I can lookup the article I mentioned above and copy their formula

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Let’s ask @WFstaff if he has any suggestions or comments.

Indeed i forget to mention radiation below 138 w/sqm doesnt count for sunshine

its not an easy thing, but the weather display software does it
what it does is it compares the expected solar radiation for your lat/long and time of day to what you are currently getting and when above a set threshold (adjustable) it counts as bright sunshine (i.e increases sunshine hours )

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What treshold is used?

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80% by default (user adjustable)

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Ok just as i said above I think this is a good way to calculate sunshine

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Where are you getting this data?

its a very complicated formula

We are very very intelligent people and some of us write very complicated formulas. I’m sure we can handle it.

I can only get to the article I mentioned above from my university. It has formula’s :wink:

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Hopefully @weather-display, in the spirit of WeatherFlow, will also share the formula he is using.

I certainly look forward to seeing what you found.

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This is very interesting:

search for “Stolzenbach” and start reading.

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Yes good find and intreresting reading unfortunally the Mathtemetics are behind my knowledge.

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There’s a solar power system value that’s equivalent hours of 100% sunlight, which is variously called Peak Sun Hours [OSLT], but that’s specific to solar power systems. You use it by multiplying your (peak) system output by those hours, and you know how many KWHR/day your system will generate.

If you want to know “how long was the sun shining today” and it’s not the number of hours between sunrise and sunset (*) you’ll need to properly define it.

(*) And as with all standards, there are so many to choose from, Civil Astronomical, Nautical, etc. Of course, in terms of “How long was the sun shining today” they are probably equivalent, unless you have a need for some extreme accuracy…

I think you’re right but our National Weather Service publice sunhours maybe I ask them … Well the Sun (as we speak of the nearest star to Earth) is always shining otherwise we’re not able to measure anything :thinking:

This is the instrument that until recently was used to measure hours of sunshine.
It has some disadvantages, but served weatherstations for a century. Nowadays it is replaced by a sensor system.