"maxSolarRad" - what is it exactly, and how is it translated?

[michael.k...@gmx.at]

If I understand "maxSolarRad" correctly, it is a calculated value that represents the theoretical solar radiation that a given station would be exposed to, at the given time, with perfect clear skies.

If this is the case, how would it translate? "maximum radiation", in my opinion, would be misleading, because:

• Without context, I would understand "maximum radiation" as the maximum radiation measured in a given timespan
• In reality, the real radiation a station is exposed to, can be more than "maxSolarRad": when the station is exposed to additional sources of radiation, other than direct sunlight. This is sometimes the case, when the uncovered sunlight plus reflected sunlight from clouds, hit the station.

So, what is a precise and concise term for this value? (Also in german @Karen K :)

[Karen K]

michael.k...@gmx.at schrieb am Sonntag, 23. Juli 2023 um 06:59:43 UTC+2:

So, what is a precise and concise term for this value? (Also in german @Karen K :)

I wrote "theoretischer Maximalwert" (English: theoretical maximum).

The formulae to calculate the value are situated in wxforumulas.py. There a link is provided:

http://www.ecy.wa.gov/programs/eap/models.html

May be, there you find more background, what the value really means and how to call it appropriately.

[michael.k...@gmx.at]

I like "theoretischer Maximalwert" (theoretical maximum): it's clear that this isn't a measured value, and, if you need more information, you know there is a theory behind, and you can educate yourself further, if you want.

But still, it lacks information, when it is presented standalone. It probably isn't very often the case, that this particular obs_type is presented without the corresponding radiation value or in a clear context. From a more technical point of view, when you present an obs_type in the form "label-value-unit", there is a need to add "radiation" to it. Which makes "theoretisches max. Globalstrahlung" or "theoretical max. radiation", even abbreviated, quite a long string. But I guess this is just as good as it gets.

And still: even theoretically there can be more radiation than "maxSolarRad" under certain circumstances. The German language has this nice feature: you can create new word by just concatenating other words. Something like "(theoretische) Klarhimmelstrahlung" or in english "(theoretical) clear sky radiation" is what is coming to my mind, when I think about it.

[Greg Troxel]

I agree that "theoretical clear-sky radiation" (with English pedant
hyphenation, required when an adjective modifies a second one instead of
the noun, although that is getting lost over time) is the proper term.

In addition to the reflections and cloud edge lensing (both of which
I've seen), there are the issues that the theory is an approximation and
the measurements have errors. Even still, I sometimes see measured over
theory, but it's close and it's the same shape.

[michael.k...@gmx.at]

Sounds sane, I'll use that for "my" skin, for the English language. For German, it still sounds a little "bumpy", as we would call it, where I am from. :D 

[Karen K]

Please remember that there are parameters in weewx.conf to adjust the calculation of maxSolarRad:

[StdWXCalculate] 

    ...
    [[WXXTypes]] 

        ...
        [[[maxSolarRad]]]
            algorithm = rs
            atc = 0.8
            nfac = 2

 

[Colin Larsen]

Karen

Is there a detailed explanation of those adjustments anywhere? I graph the maxsolarrad "under" my actual at 41south.nz (currently under reconstruction)

Thanks

Colin

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