Solar radiation problem

[PlantPot]

Now I know the following is not a proper stevenson box and probably does not give highly accurate readings, however I have used it for quite a long time and get fairly resonable results, and don't particularily want to change the se up as that would distort my previous results..

Up until now I have just had the little silver coloured sensor and take a max min at the end of every day. I have recently added the data logger (blue thing) and I have come up with a problem that I don't understand.

When there is no sun both the data logger and the original sensor are giving very simillar readins (within plus or minus 0.3°c) however when the sun comes out the datalogger can be up to 2°C higher than the other sensor  ..... Both sensors are completely shaed from the sun!  I'm guesiing the solar radiation is somehow being reflected and absorbed by the dark colours of the sensor? I'm not really wanting to shield it from the north as that affects ventilation, so should I just paint the sensor white?

 

Edited September 12, 2014 by PlantPot

[4wd]

Not sure what's best to do but you got the reason right I think.
It's funny but on those days with *bright* cloud layer your current set up probably isn't much more screened than if it were facing south.
You'll also be getting slightly lower night temps as the equipment will chill down like a car roof giving something more like a ground temperature under clear skies.
You point about not wanting to change the set up as it somehow invalidates the earlier records is fair, but also demonstrates why a reasonably long-lived and versatile enclosure is a good thing to have.

Can't say I like the idea of paint on it myself, but more screening wouldn't need be all that fancy so long as it let air in at the bottom and out at the top.

[PlantPot]

I must experiment with some shielding from the north.

 

I assume your concern for more of a "ground temperature" reading comes from its openess to the north?  The whole thing is sighted under a rather large bird table which does seem to protect it from the 'car roof' scenario. 

 

My readings so far from the small silver sensor have not been too dissimillar to a nearby 'official' weather station so I am quite happy, just dissapointed the data logger is giving such high readings when the sun comes out.

 

 

I would quite like a proper stevenson box for the front garded, but the wife would just not allow it :-(

 

this measring temperature stuff is not all that straight forward is it.

[reef]

Have you considered the Davis shield? Im not entirely sure if your sensor would fit, but its probably one of the best passive stations you can buy outside of a proper Stevenson screen:

 

https://www.weathershop.co.uk/shop/brands/davis-instruments/accessories/davis-7714-radiation-shield

http://www.skyview.co.uk/acatalog/DAV_7714.html

 

Info:

 

http://www.davisnet.com/product_documents/weather/manuals/07395-093_IM_07714.pdf

[PlantPot]

At 82 smackeroonies it hasn't taken me long to consider

 

I am really just wanting the blue sensor to give the same reading as the silver sensor when the sun is shining - even though neither of them are in the sun.

[h2005__uk__]

How exposed is the whole screen? Does the sun shine on it all day or is it only at certain times of the day?