Massive Discrepancy between Theoretical Max & Solar Radiation Belchertown Graph

[Kevin Crivelli]

I've checked to ensure that my weewx configuration is set to "prefer software" for getting Theoretical Max however, instead of having the bell curve of the max with Solar Radiation and UV Index I have Solar Radiation and UV Index but the numbers for the max are extremely low in comparison. I am providing a screenshot to show you what I mean. Also I am using the graph setup directly from the Belchertown Charts Document so I'm not sure why this is what is happening. 

I'm providing two screenshots. one with just UV Index and Max and one with all 3. 

You'll see I do have data for the Max but it's wildly lower in wm^2 than that of solar radiation 

[Greg Troxel]

Kevin Crivelli <kevinjc...@gmail.com> writes:

> I've checked to ensure that my weewx configuration is set to "prefer
> software" for getting Theoretical Max however, instead of having the bell
> curve of the max with Solar Radiation and UV Index I have Solar Radiation
> and UV Index but the numbers for the max are extremely low in comparison. I
> am providing a screenshot to show you what I mean. Also I am using the
> graph setup directly from the Belchertown Charts Document so I'm not sure
> why this is what is happening.
>
> I'm providing two screenshots. one with just UV Index and Max and one with
> all 3.
>
> [image: max1.JPG][image: max2.JPG]

(text mode mail reader here :-)

> You'll see I do have data for the Max but it's wildly lower in wm^2 than
> that of solar radiation

Assuming you are at mid latitudes (40ish), I would expect theoretical
max solar radiation to peak around solar noon around 1000 W/m^2 earlier
in summer and maybe 900 now. Looking at my own graphs (42N, Boston), I
eyeball 870 W/m^2. On clear-sky days the measured values are fairly
close to the theoretical max curve. On partly cloudy days the peak
measured values and the "max observed" values are higher, but not
massively so.

However, your values are just crazy. 67,000 W/m^2 is simply not
possible on earth. A theoretical max of 874 W/m^2 is totally
reasonable, depending on where you are.


You mentioned Acurite, so you should be clear on what sensors your
station actually has. It is highly likely that it measures illuminance
in lux (= lumens/m^2) and not irradiance in W/m^2.

One cannot convert lux to W/m^2, but people do anyway.

Read carefully:

https://github.com/weewx/weewx/wiki/Watts-and-lux/

Probably you are storing illuminance in an irradiance field, and there
seems to be historical confusion in the wview schema which IIRC has a
field labeled "radiation".