How are sunshine hours calculated

I have had partly cloudy skies all day but the sunshine hours are showing 1.5 hours? Anyone know how this is calculated?

I would think that solar radiation (UV) was coming through the clouds resulting in sunshine hours being calculated. As in getting a sun burn on an overcast day. :?

I would think that the number of hours would have been more than 1.5 hours? I guess I’m asking exactly how the hours are calculated. Is it based on ANY sunshine hours or does it have to be totally sunny for an hour to been consider it an hour.

You have asked a good question. I wan’t to know.

Here is something from NOAA’s site below.
http://www.crh.noaa.gov/lsx/climate/glossary.htm

For record purposes, the term "sunshine recorded" means that the amount of sunlight received at the surface was strong enough to cast a distinct shadow. This means that you could have a thin overcast and still record sunshine. The data is measured by an electronic sensor.

Maybe Brian will tell us how WD calculates the Sunshine hours.

its determined by the threshold settings you have set under setup, solar setup…
one problem with the temperature solar sensor is the lag in the sensor heating up once the sun out behind the clouds…

the traditional method is wtih a cambell stokes sunshine recorded…and the sunlight needs to be strong enough to burn a trace on the paper…

so the answer greg maybe tweak up your sunny threshold