Detecting Cloudy or Clear night

[Bashy]

Hi again, i know you say it needs to have a black bottom but i have been monitoring
mine as it is without the black, last night it was partly cloudy, well, more like very high
thin cloud, you could see the moon haloing through the thin cloud and my difference was
+0.4^oC and tonight its very over cast with a slight break through of the moon light and
the difference is +0.2^oC, to summarise;

• +0.4^oC = thin layer of high cloud (moon haloing through)
• +0.3^oC = Partly Cloudy
• +0.2^oC = Thick cloud with moonlight slightly breaking through in places

I have not had a clear night yet so i cannot comment as to whether or not there will be a big
difference or not, but, im sure i can vaguely remember a significant difference between the 2
sensors in the past, I am going to go through my logs to see if i can find anything

Anyway, how does this look at the moment Brian, is it possible it might work without having to black it?

[weatherc]

I have mine solarsensor in a plastic tupperware-type pot what is white and light blue and at the moment mine main temp is 6.0 and solarsensor is 3.8 and outside is partly cloudy, so I should follow it and give it a try and try to set the limits in WD after that

[Weather Display]

Bashy, it needs to be colder in clear skies (i.,e a black body)
thats how WD is expecting it to occur
you need to make it a black body, no other way around it

[Bashy]

Ya cant fault a guy for trying

[BrianM]

Hi Brian

Outside 14.3, Solar 13.8 Diff = 0.8

Overcaset setting 0.4
Clear Setting 2.1 Diff = 1.7

But Icon showing clear sky, does not seem correct?

Re Brian

[Weather Display]

what I will need to do is run some dummy values through my code
but i am away for the weekend (leaving in a little while)

[eongibier]

Bojour,
Peut on mettre la sonde dans un bocal plastique noir ?

Merci
Serge

[eongibier]

Hello,
In does the bottle only the bottom of the bottle have `it to be painted in black?

Thank you
Serge

[skyewright]

In does the bottle only the bottom of the bottle have `it to be painted in black?

I'm trying out Brian's suggestion of putting black tape around the lower half of my jar.

I only added the tape yesterday evening and we haven't seen any clear sky (night time or daytime!) since then, so it's too early yet to say how well it's working or what effect (if any) the tape has on day time figures.

See picture earlier in the thread for the jar before adding the tape. I'd attach a picture of how it is now, but it's too wet at the moment to take a decent photo.

[weatherc]

Hmm..Seems this want yet work together with VP2, I have a (1-wire)extrasensor now allocated ok and set clear to -1.5, difference is now -1.6 and WD still shows cloudy

(Same as "normal" solar in a jar, don't work either with VP2)

Henkka

[Bashy]

Hi folks...

I know Brian said that this would not work for me untill i had blacked out the bottom of my Lab flask...
But, last night a neighbour 3 doors down decided to have an all night party and i got woke up at 4am
with his loud music thumping away, anyway, i decided to check WD cause normally when i get up at
that time and DONT check WD then get up in the morning I find that it crashed around the time i should
have checked it, so i did this morning about 4:30 just before i went back to bed, WD was running great,
I also checked the solar and that was at 11.2^oC i then check the out side temp and that was at 12.2^oC
So i took a look outside and you could not get a clearer night, the moon and the stars were clearly visible.

so, this is now telling me that i should not have to black it out? It seems to register enough to make the
adjustments in the new settings, To Summarise;

    * +0.4oC = thin layer of high cloud (moon haloing through)
    * +0.3oC = Partly Cloudy
    * +0.2oC = Thick cloud with moonlight slightly breaking through in places
    * -1.0oC = Clear night

what do you reckon folks? Does this look like it will work without blacking out the bottom or
do i still need to black it out?

[skyewright]

To Summarise;

    * +0.4oC = thin layer of high cloud (moon haloing through)
    * +0.3oC = Partly Cloudy
    * +0.2oC = Thick cloud with moonlight slightly breaking through in places
    * -2.0oC = Clear night

what do you reckon folks? Does this look like it will work without blacking out the bottom or
do i still need to black it out?

I can't give an opinion yet on the blacking out of the bottom of my jar. I think there may be a bigger difference, but I've not seen enough variation in conditions yet.

However, your suggested intermediate differences don't make sense to me. You have a positive increase in difference between thick cloud and thin cloud, then a negative jump to no cloud at all.

The -2.0 C difference for no cloud seems sensible if I've understood the logic of the idea. It's the others that seem odd. I think you need to study the figures for a bit longer yet to spot a full pattern.

However, maybe what you have is enough at present? Unless I'm missing something obvious (quite possible!) we only have 2 levels to set at present, i.e. using  v10.37L b11 when I look in Setup => Advanced/Misc Settings => Boltwood cloud sensor, I only see settings for Overcast and Clear.

[Bashy]

I binned the paper with the other figures on it i may very well have it the wrong way round pmsl...
knowing me thats what it will be, but last night it was definitely a -2.0

[Bashy]

Right then, i just double checked my logs, i must have been half asleep at 4:00am
cause i wrote down 13.2 but it was actually 12.2 for the solar and 11.2 for the temp
so i got it the wrong way round as well pmsl... best go and edit my post above 

[skyewright]

Maybe a picture paints a thousand words...

Attached is a graph showing my main outdoor temp and the solar jar temp for the last 24 hours.

For most of the night (sunset ~19:45, sunrise 6:53) the solar was around 0.2 to 0.3 above outdoor. I'm assuming that that represents 'overcast' for my set up (the small positive difference may just be a matter of calibration differences between the 2 sensors).

A few times the solar dropped below the outdoor, e.g. just before 23:00 and between 00:30 and 02:00. I'm assuming that those times represent a clearer (but not totally clear) sky.
It so happens that I did look out just after 11pm and the moon was clearly visible, but with halo, for a short while - so maybe broken cloud? The general drop in temp at those times would also support the idea of a break in the cloud.

Also attached a picture of the "modified" solar jar.

I got a piece of black plastic, wrapped that around the bottom half of the jar, then wrapped black tape around that - the idea of the inside plastic layer being that if I decide to remove the black bottom I won't be left with a mess of adhesive to clear off the jar. 

We've not had any 'proper' sunshine since I made the mod, but so far as I can tell the black bottom seems to have had no adverse affect daytime use.