The main cause of higher than expected insolation is scattered light being added to direct light.
Thin clouds are a good source of scattered light, but if you have nearby structures, such as walls, above the sensor then they can also contribute. Your very high ratio early morning is almost certainly indirect light, and it might be that the "theoretical" calculation only gives a direct light value (I haven't looked at the code). Finally, theoretical calculations still have to take into account atmospheric absorption by minor gases and particles that are not known locally. If the calculations assume a moderate level of pollution but you have very clear air then you will see higher than expected insolation, but your readings look too high to be explained by just that. On Sunday, 20 December 2020 at 11:36:19 pm UTC+10 [email protected] wrote: > OK, update on this.. > > I made sure the consoles and weewx had the exact same lat/long. They were > very close but not exact. > > I'll just use one station for this today, which is the one in MA at 42.5 > latitude. > > It is completely overcast today, at least so far. > > I ran this query against my archive table: > > SELECT datetime, convert_tz(from_unixtime(datetime),'GMT', 'US/Eastern') > as Date, radiation, round(maxSolarRad,0) as maxRad, round(radiation - > maxSolarRad, 0) as delta FROM weewx_ma.archive where radiation > 0 order by > datetime desc limit 288; > > Here are the results as of now: > > '1608471000','2020-12-20 08:30:00','38','82','-44' > '1608470700','2020-12-20 08:25:00','39','72','-33' > '1608470400','2020-12-20 08:20:00','47','63','-16' > '1608470100','2020-12-20 08:15:00','44','53','-9' > '1608469800','2020-12-20 08:10:00','38','44','-6' > '1608469500','2020-12-20 08:05:00','32','36','-4' > '1608469200','2020-12-20 08:00:00','29','28','1' > '1608468900','2020-12-20 07:55:00','26','21','5' > '1608468600','2020-12-20 07:50:00','26','15','11' > '1608468300','2020-12-20 07:45:00','20','10','10' > '1608468000','2020-12-20 07:40:00','16','6','10' > '1608467700','2020-12-20 07:35:00','12','3','9' > '1608467400','2020-12-20 07:30:00','10','1','9' > '1608467100','2020-12-20 07:25:00','5','0','5' > '1608466800','2020-12-20 07:20:00','4','0','4' > > So I am having this issue on a cloudy day with lat and long aligned. > > Is anyone else seeing this in their environment?? > > On Saturday, December 19, 2020 at 4:48:52 PM UTC-5 [email protected] wrote: > >> Double-checked on both counts. >> >> On Saturday, December 19, 2020 at 2:34:50 PM UTC-5 vince wrote: >> >>> On Saturday, December 19, 2020 at 10:18:43 AM UTC-8 [email protected] wrote: >>> >>>> Looks like I might have unlocked some secret of the universe because my >>>> solar radiation numbers are regularly above the "theoretical max" as shown >>>> in the Belchertown skin. >>>> >>>> >>> Many stations emit readings like this (WeatherFlow to name one). >>> >>> I guess I'd suggest making sure you have pyephem installed and that your >>> lat/lon in weewx.conf is correct. >>> >>> >> -- You received this message because you are subscribed to the Google Groups "weewx-user" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/weewx-user/42e7357e-1046-4145-9c39-932473483cf1n%40googlegroups.com.
