Dark night - 46.0 lux

[Spanky]

Hi,

I've just run up Cumulus today so that I can get the solar data from my WH-3081 weather station - have been running WD until now but there seems to be a problem with getting the solar data incorporated with that application.
Install was easy, and everything seems to be working well for the most part.

I was wondering if there is a way to calibrate the Solar / Light reading as it's a dark night here now but it's reading 46.0 lux ?
From a a table I found on wikipedia (below) it looks as though this is a fair way out.
Illuminance Example
10−4 lux Total starlight, overcast sky
0.002 lux Moonless clear night sky with airglow
0.01 lux Quarter moon
0.27 lux Full moon on a clear night
1 lux Full moon overhead at tropical latitudes
3.4 lux Dark limit of civil twilight under a clear sky
50 lux Family living room

I had a look in Configuration / Calibration but couldn't see anything there for the solar data.

Thanks,
Shane.

[steve]

Is the strange figure showing on the console or only in Cumulus?

[Spanky]

Hi Steve,

Shows that same value on the console too, but I don't know of any way to correct it there either.

Cheers,
Shane.

[steve]

Right; I just wanted to make sure it wasn't a bug in the code that interprets the data.

I can put in calibration settings for the light readings, it's straightforward enough. I'd expect it to be reading zero at night, so I'm not quite sure what settings you would use - subtract 46? What figure do you get at midday on a sunny day?

[broadstairs]

Although I have a different station when my solar sensor started reading > 0 after dark it was a failing sensor and I had to replace it. I suspect of you get 46 lux after dark you may have a similar issue

Stuart

[Spanky]

It seems to be functioning - i.e it's currently reading 6783 lux this afternoon, so it's not just presenting the one erroneous reading.

I missed actually looking at the reading at midday, but the relevant line from the log file is below if that helps:
23/05/11,12:00,13.8,89,12.0,12.2,17.3,280,0.0,0.9,1008.3,46.2,20.7,55,14.8,12.9,13.8,2.0,155,0.00,0.00,12.0,524,0.9
(it's been intermittently rainy and cloudy today so the readings have been all over the place)

Cheers,
Shane.

Although I have a different station when my solar sensor started reading > 0 after dark it was a failing sensor and I had to replace it. I suspect of you get 46 lux after dark you may have a similar issue

Stuart

[steve]

Thinking about it, 46 lux is actually a very small value; using the default conversion factor in Cumulus (0.0079) that's only about a third of a W/m2, so it's not a completely unreasonable figure given the equipment, so probably a tweaking of minus 40 with a calibration setting would do the trick.