Wikipedia:Reference desk/Archives/Science/2025 July 14

Science desk
< July 13	<< Jun | July | Aug >>	July 15 >

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is a transcluded archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

July 14

Solar irradiance

We have a detailed but annoyingly lacking in numbers article solar irradiance. It says things like the average irradiance averaged over the whole Earth for a whole year is 1361 W/m^2. But I was hoping to know how to find the instantaneous irradiance at a given ___location and time. For example, in San Francisco at 2:17 PM on July 4 of this year (an arbitrary date I just made up). Is there an alternate place in Wikipedia or elsewhere, where I could find this kind of info? Other than cloud cover and small fluctuations in solar output, is there something nebulous or hard to compute about the quantity? I'm ok with being off by up to a few percent, for solar power calculations. Alternatively, I'd be content to know the total wattage radiated by the Sun, as I can figure out the rest from data that I do know how to find.

It looks like the article was written with studying radiative forcing of global temperature, where they want very accurate data but averaged across large areas and times. THanks. 2601:644:8581:75B0:4E7A:7983:893E:AA0 (talk) 13:17, 14 July 2025 (UTC)[reply]

The article on the sun gives in its infobox both its luminosity and mean radiance. Are these the numbers you want? Mike Turnbull (talk) 15:58, 14 July 2025 (UTC)[reply]

Doh! Thanks. 2601:644:8581:75B0:4E7A:7983:893E:AA0 (talk) 18:04, 14 July 2025 (UTC)[reply]