Temperature in jar for solar observation

[Peter Leban]

I've few weather stations and not all have a solar sensor. For Vantage Vue, I was using Weather Display which has a very nice feature that correlates the temperature in a jar to external temperature to plot the solar curve. I'm not interested in the very accurate value but I use this value to calculate sky conditions (sunny, partly cloudy, cloudy, etc.). I switched to weewx now which doesn't have this feature (I think). My sensor is connected to the 1-wire-to-USB interface.

I probably could read the temperature value from a jar over 1-wire, then I'd use the external temperature and also set the offset (e.g. 15degC) between the two temperatures to say when the sky is clear and sun is highest (at noon/1pm). I also have a maxSolarRad value that would be my limit for that time of the day.

I wonder how to plot the "solar" curve from sunrise on. Is the temp-offset always considered as "15 degC" for sunny conditions or also this offset slides over the curve? Anyone experimented on this?

For the Weatherflow station, I implemented the logic to say the sky conditions but there I get the solar value from the station itself.

Thanks.

[Greg Troxel]

Peter Leban <pete...@gmail.com> writes:

> I wonder how to plot the "solar" curve from sunrise on. Is the temp-offset
> always considered as "15 degC" for sunny conditions or also this offset
> slides over the curve? Anyone experimented on this?
> For the Weatherflow station, I implemented the logic to say the sky
> conditions but there I get the solar value from the station itself.

My advice is to put this someplace and then gather data for a number of
full-blue-sky days, noting when it's in the sun. Then you can try to
curve fit the data to the calculated irradiance. Or the irradiance
from a nearby station.