On 10/06/2014 10:09, Desperate Dan wrote:
If the wooden screen wasn't maintained properly, painted regularly, then the wood would absorb water, thus cooling the screen by evaporation. Obviously, this doesn't happen with the plastic version. I have noticed that the shiny white on the plastic does grow dull (almost matt) with age. I'm sure any trials have been conducted with nice new screens so what happens over time has probably never been looked at.


I would not have thought the gloss vs matt finish on the white outside
would matter so much although matt is probably better there.

It is an interesting question as to what an ideal air temperature
measurement enclosure should be like. The classic Stephenson screen used
by meteorologists almost certainly introduces small systematic errors in
strong sunlight and also with a clear night sky.

And also depending on its surface wetness and windspeed at the time.

OTOH all historical data is recorded with this methodology and so any
radical change would put a discontinuity in the records.

I expect it could be important though at tropical latitudes where the
sun can get right overhead and beat down on the roof of the enclosure.

--
Regards,
Martin Brown