Free to a good home ...

For discussion of any observing equipment, from Stevenson Screens and manual instruments to electronic weather stations

Free to a good home ...

Postby Stephen Burt » 2012 Mar 24, 10:33

I'm about to replace my existing large wooden Stevenson screen with one of the new Metspec plastic-and-aluminium models, and the existing screen will therefore shortly become surplus to requirements.

The screen is mostly in excellent condition, although there is some rot starting to appear in one corner. Unfortunately the work required is beyond my woodworking skills, but with a little attention I'm sure it would last another 20 years.

There's also a painted steel stand to fit. Both are currently in use, but will be available at some stage during April. Because of their size, they will have to be collected.

The screen's external dimensions are 112 x 40 x 60 cm (W x D x H), and the stand is 115 x 43 x 150 cm approx (30 cm or so is sunk into the ground). There is a photograph of the screen in my station entry in the COL Directory. Internal fittings and thermometers etc are not included.

If you're interested, please drop me a PM on this forum or contact me at the e-mail address given in the front of the bulletin.

SB
-----
Stratfield Mortimer, Berkshire - central southern England
51.4°N, 1.0°W, 60 m AMSL, station grade A - AAAA47R
Records commenced here 1987 - local records available back to 1862
The Weather Observer's Handbook: www.measuringtheweather.com
Stephen Burt
 
Posts: 247
Joined: 2011 Dec 02, 19:36
Location: Stratfield Mortimer, Berkshire; a well-exposed rural site, 10 km SW of Reading

Re: Free to a good home ...

Postby Dave Evans » 2012 Mar 25, 22:03

I would be interested to hear your comments on the plastic screen, Stephen. I had one supplied by the Met' Office two years ago; it works well enough as a screen but the interior is completely black and, at least to my eyes, it makes it very difficult to read the vertically mounted thermometers ( wet and dry bulb ) when the sun is shining to the south/south east.
The black interior. combined with glare from the sun seems to negate the contrast between the spirit column and the white background of the thermometer. At times I find the only way to read the thermometers relatively quickly and accurately is to hold a piece of white card behind the thermometer to provide a contrast.
I've no idea on the thinking behind making the screen interior black as the traditional white finish on the wooden screens has worked admirably for years.
Dave Evans
 
Posts: 32
Joined: 2012 Feb 22, 13:58
Location: Middleton Moor, Derbyshire Peak District. 321 m

Re: Free to a good home ...

Postby Stephen Burt » 2012 Mar 28, 08:07

Dave, I've had my Metspec plastic screen installed for just over 6 months now, running as an overlap against my existing large wooden Stevenson screen just over 10 metres away, so have some experience with it.

I've not found reading the thermometers to be a problem in the new screen. It's a little worrying that you consider there is glare inside the screen, as this would seem to indicate that more solar radiation is finding its way inside than should be the case. I usually only open mine at the 0900 ob, when the sun is in the south-east rather than the south-west, and of course I have yet to observe conditions during the summer half-year, but to date I would not consider glare to be a problem. I also use yellow-stemmed sheathed thermometers, which might help with the contrast - have you tried those?

The rationale behind the black interior is indeed a bit of a puzzle, one Ian Strangeways and myself have spent several years trying to get to the bottom of, with rather ambiguous results. Tests run by the Met Office in 2000/01 showed that black-interior screens had slightly lower maxima than white interior versions in strong sunshine, and thus were presumably more effective at blocking solar radiation. Other tests have been run by other authorities, most recently one by Campbell Scientific in the UK, and the black screens do seem to offer slightly better performance than the white interior versions. (If you'd like to see copies of the reports, please drop me an e-mail and I'll send them to you; I've also covered the topic in my forthcoming book on weather observing, which will be published in July - http://www.cambridge.org/9781107662285 )

While accepting that the tests were rigorous and the reported differences are genuine, I'm not 100% convinced that the difference is due simply to the black plastic material used having different (more opaque) radiative properties in the infra-red than the equivalent white plastic, rather than their colour in the visible spectrum. A black-interior plastic screen is also a poor choice for a site where the screen is opened several times a day, as it would have been before most sites moved to remote-reading and/or logged equipment, as the temperature does rise quickly in sunshine when the door is opened, more so than a white interior model. I keep mine firmly shut during the day!

I've compared the observed max and min temperatures in the two screens carefully over the last 6 months, and find the differences small - the Metspec screen appears to be slighly more responsive, probably because it is smaller than the large wooden screen and thus has less thermal inertia. However, the differences are within calibration tolerances, so I'm happy that swapping the wooden one for the plastic one isn't going to disrupt the continuity of my records.

SB
-----
Stratfield Mortimer, Berkshire - central southern England
51.4°N, 1.0°W, 60 m AMSL, station grade A - AAAA47R
Records commenced here 1987 - local records available back to 1862
The Weather Observer's Handbook: www.measuringtheweather.com
Stephen Burt
 
Posts: 247
Joined: 2011 Dec 02, 19:36
Location: Stratfield Mortimer, Berkshire; a well-exposed rural site, 10 km SW of Reading

Re: Free to a good home ...

Postby Dave Evans » 2012 Mar 29, 08:36

Hi Stephen, thanks for the reply.
My problem lies not with solar radiation entering the screen ( like you I open mine only at 0900, and it faces north)
but is a combination of the following; I need reading spectacles, or a reading glass, to see the graduations on the thermometers in sufficent detail to read them accurately ( the joys of getting older! ) and the combination of the sun shining towards me and the black interior of the screen causes a reflection of the landscape behind me on the spec's/ reading glass which all but obscures the markings on the thermometer. When I mentioned glare I should have been more specific.
For some reason this is only a problem with the vertically mounted thermometers and not the max' and min' which are mounted almost horizontally ( mine too are all sheathed and have a yellow background ).
In my original wooden screen all the thermometers ( all but one of which have a white background and are all sheathed ) are mounted almost horizontally and I've never encountered any problem with reading them, no matter how bright the sunshine, as the white interior prevents the reflection of the background on my reading glass/spec's.
As I mentioned I've overcome the problem by always taking a small piece of white card to hold behind the vertically mounted thermometers, this cuts out the background reflection and the thermometers are easily read.
I suppose the alternative would be to have all the thermometers mounted a few degrees from the horizontal but there seems to be no facility for adapting the Metspec screen in this way.
Dave Evans
 
Posts: 32
Joined: 2012 Feb 22, 13:58
Location: Middleton Moor, Derbyshire Peak District. 321 m

Re: Free to a good home ...

Postby Stephen Burt » 2012 Apr 03, 09:30

The screens have now been swapped over, and the large wooden Stevenson screen plus stand as described below is available free to a good home. It can be collected by arrangement.

SB
-----
Stratfield Mortimer, Berkshire - central southern England
51.4°N, 1.0°W, 60 m AMSL, station grade A - AAAA47R
Records commenced here 1987 - local records available back to 1862
The Weather Observer's Handbook: www.measuringtheweather.com
Stephen Burt
 
Posts: 247
Joined: 2011 Dec 02, 19:36
Location: Stratfield Mortimer, Berkshire; a well-exposed rural site, 10 km SW of Reading

Re: Free to a good home ...

Postby Darren Rogers » 2012 Apr 05, 20:24

Just a general point/question - can the new Screens fit onto the old stands?

I seem to have this feeling that they don't. If not, isn't that a little bit daft?
Darren Rogers
Maulds Meaburn
Cumbria (Half way between Shap and Appleby)

http://www.mauldsmeaburnweather.co.uk
Darren Rogers
 
Posts: 145
Joined: 2011 Nov 27, 20:22
Location: Cumbria - half way between Shap and Appleby in the Eden valley

Re: Free to a good home ...

Postby Stephen Burt » 2012 Apr 06, 06:57

The new (Metspec) plastic and aluminium screen is half the size of the existing large wooden screen, so while it would probably be possible to affix it to the 'old' stand, it would look a bit odd and would probably not be all that secure. It's quite possible that an existing stand for a wooden screen of the same size as the newer Metspec screen would fit the latter, but not having one to hand I can't say for sure ...

SB
-----
Stratfield Mortimer, Berkshire - central southern England
51.4°N, 1.0°W, 60 m AMSL, station grade A - AAAA47R
Records commenced here 1987 - local records available back to 1862
The Weather Observer's Handbook: www.measuringtheweather.com
Stephen Burt
 
Posts: 247
Joined: 2011 Dec 02, 19:36
Location: Stratfield Mortimer, Berkshire; a well-exposed rural site, 10 km SW of Reading

Re: Free to a good home ...

Postby Stephen Burt » 2012 Apr 27, 20:54

Bumping up to the top ... if anyone would like this, please let me know as space considerations will mean I'll have to dispose of it soon, and it still has at least 10 years life left in it ... !

--
I'm about to replace my existing large wooden Stevenson screen with one of the new Metspec plastic-and-aluminium models, and the existing screen will therefore shortly become surplus to requirements.

The screen is mostly in excellent condition, although there is some rot starting to appear in one corner. Unfortunately the work required is beyond my woodworking skills, but with a little attention I'm sure it would last another 20 years.

There's also a painted steel stand to fit. Both are currently in use, but will be available at some stage during April. Because of their size, they will have to be collected.

The screen's external dimensions are 112 x 40 x 60 cm (W x D x H), and the stand is 115 x 43 x 150 cm approx (30 cm or so is sunk into the ground). There is a photograph of the screen in my station entry in the COL Directory. Internal fittings and thermometers etc are not included.

If you're interested, please drop me a PM on this forum or contact me at the e-mail address given in the front of the bulletin.

SB
-----
Stratfield Mortimer, Berkshire - central southern England
51.4°N, 1.0°W, 60 m AMSL, station grade A - AAAA47R
Records commenced here 1987 - local records available back to 1862
The Weather Observer's Handbook: www.measuringtheweather.com
Stephen Burt
 
Posts: 247
Joined: 2011 Dec 02, 19:36
Location: Stratfield Mortimer, Berkshire; a well-exposed rural site, 10 km SW of Reading

Re: Free to a good home ...

Postby Graham Webster » 2012 Sep 04, 17:45

Hello. This is my first post in the new COL forum.

I got a Metspec screen from the Met Office in November 2006. I built my own stand out of wood. I like to keep my screen clean just like a new car. In doing so I have managed to break many many louvres over the years and I really need to buy a new one. One of the legs of my wooden stand snapped in the Jan 3rd storm and I need to get it replaced before the stand and screen topple over. I tried to buy a new stand from Metspec, but I am still waiting. The Metspec screens and stands can be bought from the UK Weathershop, but there is a 6 week waiting list. I think Metspec are a waist of time! I've tried to get a screen direct from the Met Office, but they don't sell equipment to the public anymore (since 2007?).

Steven, how did you manage to get your hands on a Metspec screen?

Recentl, I have discovered than Casella make two versions of plastic screen. The Advanced Instrument Shelter and the lastest model, the Advanced small instrument shelter. The latter is a direct replacement for the old small wooden screens so the small advanced instrument shelter should fit on an iron stand. I have a new unused iron stand so I might buy a small intrument shelter from Casella and forget about Metspec.

Steven, do you know about the Casella screens? Do they perform as well or better than Casella???

Cheers,
Graham.
Graham Webster
 
Posts: 9
Joined: 2012 Sep 04, 17:11
Location: Baintown, Fife. 125m asl. Firth of Forth, 3km to south-east. Hill, 205m asl 1km to NNW.

Re: Free to a good home ...

Postby Graham Webster » 2012 Sep 04, 17:46

Darren Rogers wrote:Just a general point/question - can the new Screens fit onto the old stands?

I seem to have this feeling that they don't. If not, isn't that a little bit daft?


Metspec screens no! The Casella Advanced Small Instrument Shelter is a direct replacement for the small wooden screens and fits onto the traditional iron stands.
Graham Webster
 
Posts: 9
Joined: 2012 Sep 04, 17:11
Location: Baintown, Fife. 125m asl. Firth of Forth, 3km to south-east. Hill, 205m asl 1km to NNW.

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