Author Topic: Steel Gauges Solar Radiation  (Read 2416 times)

Blicj11

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Steel Gauges Solar Radiation
« on: June 03, 2014, 03:28:47 AM »
I have a new Solar Radiation sensor. Can someone explain what is meant by the message included in the popup graph? Specifically,
  • Why is something 700% of maximum? What does it mean?
  • What is the theoretical maximum reading telling me?

I am attaching a screenshot.

Thanks.

Blick


Felix

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Re: Steel Gauges Solar Radiation
« Reply #1 on: June 03, 2014, 05:11:14 PM »
Good questions, I'll be waiting to see the answers.

I had a couple solar radiation explanations URLs bookmarked but, of course, they don't address WeatherCat's gauges.

http://nws-katestone.com.au/dairy_thi/MajorTownFC.html

http://home.iprimus.com.au/nielsens/solrad.html

WCDev

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Re: Steel Gauges Solar Radiation
« Reply #2 on: June 03, 2014, 06:33:18 PM »
That's the current potential solar radiation - you actual is 56 and the potential (according to the model) at that time is 8, hence the 700% of maximum.

More info can be found at:
http://athena.trixology.com/index.php?topic=785.msg6837#msg6837

Blicj11

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Re: Steel Gauges Solar Radiation
« Reply #3 on: June 04, 2014, 03:06:57 PM »
Thanks Felix and Stu:

I have done a bit more digging around and learned that using the Ryan-Stolzenbach model, sunshine occurs when readings meet or exceed a certain percentage of the theoretical potential value. This is apparently how WeatherCat calculates sunshine hours.

Stu, as WeatherCat uses an atmospheric transmission factor of 0.8, does that mean that sunshine occurs when the readings exceed 80% of the potential value or am I confusing the atmospheric transmission factor with something else?
Blick


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Re: Steel Gauges Solar Radiation
« Reply #4 on: June 04, 2014, 06:44:33 PM »
Hi Blick,
The potential solar radiation was added to support the Steel Series gauges (presented as the CPS$ tag) - it isn't used anywhere else in WeatherCat. The 0.8 transmission factor is the default for the model, which provides an estimate of the maximum solar radiation for your location for a given date/time.

Sun hours are calculated in WeatherCat via simulation of a Campell-Stokes sunshine recorder, this uses solar radiation and humidity to calculate whether the paper would burn or not - the burns are added up over time to calculate sun-hours.


Blicj11

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Re: Steel Gauges Solar Radiation
« Reply #5 on: June 04, 2014, 11:07:00 PM »
Thanks for sorting me Stu.
Blick


Blicj11

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Re: Steel Gauges Solar Radiation
« Reply #6 on: June 15, 2014, 03:39:58 AM »
I have another question about the popup graphs for solar radiation. I have noticed that although the maximum reading is stated correctly on the popup graph, the graph itself does not come close to showing the maximum in the graph. For example, the screen shot I posted earlier in this thread states that today's maximum reading is 1187 whilst the graph shows the maximum to be about 800. Similarly, in the screenshot attached to this post, today's maximum is 1227 whilst the graph shows the highest reading at about 600. I received a WeatherCat email today at 13.56 informing me of a new record high radiation reading of 1227. The graph for that same time period is considerably less. I assume the graph is showing average readings but I would like someone to confirm why there is a difference. Thanks.
Blick


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Re: Steel Gauges Solar Radiation
« Reply #7 on: June 15, 2014, 08:13:54 AM »
Looks to me like some filtering is being applied - check the 'Basic Graph Display Filter' is fully off in the 'Location/Colors' tab of WeatherCat's preferences.

Blicj11

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Re: Steel Gauges Solar Radiation
« Reply #8 on: June 15, 2014, 01:23:07 PM »
I'm an eejit. I always wondered what that filter did. I have experimented with it a wee bit this morning and now I know.  Thanks Stu.

One observation, when you quit WeatherCat and restart it, that filter defaults at startup to state that it is Off, but the slider is in the maximum position. However, the slider itself does not actually match up with the amount of filtering until you slide it all the way to the left and actually turn it off. After that, the slider matches the amount of filtering. If you don't do that after a restart, the filter says that it is off, but it actually defaults to the last setting in which you left it.

Again, thanks Stu.
Blick