[wxqc] Opinions please -- New design for solarradiation shielding

[Mitch Morberg]

Hi,

I have been experimenting with weather equipment for 30 years. I have found that just shielding
the existing radiation shield with 3/8" plywood painted gloss white with plenty of room for air
movement does an excellent job. See the link below for pictures.

http://www.mlmweather.com/Station.htm

Comparing my station CW0288 to the closest ASOS Stations

http://weather.gladstonefamily.net/qchart/C0288?date=&addnl=KLXL&addnl=KPNM&addnl=KSTC&addnl=KJMR&addnl=KCBG&addnl=KBRD&Add+to+charts=Add+to+charts&.cgifields=addnl

Mitch CW0288 http://www.mlmweather.com


--- Geoffrey Dick <wa4ikq at nevets.oau.org> wrote:

> 
> Bryce,
> 
> Looking at your 28-day Day and Night Temperature errors, the readings 
> are fairly good.   The lastest indication for Saturday was only -1.3
> degrees in the day, and +1.7 deg at night.   
> 
> Are you game for trying an experiment to bring the day and night values
> closer together?   Try wrapping the PVC with aluminum foil.
> 
> ...................................................................
> 
> Thomas,
> 
> What does your Physics background tell you about white PVC piping in
> regard to being a perfect reflector of solar radiation?  How much
> thermal absorption does the PFC material generate?  Do you recall
> how standard temperature radiation shields settled on a white color?  
> 
> ...................................................................
> 
> ALL,
> 
> It may be a bit early to report, but over the last 12 days I have been
> operating with strips of aluminum foil covering the outer surface of 
> the gill vents of my radiation shield, and I have noted steady  
> improvement in the CWOP 28-day day numbers without adjusting the 
> controller offset.  
> 
> My 28-day numbers are posted at:
> http://weather.gladstonefamily.net/site/AS140  see Temperature nos.
> 
> My numbers, for several months prior to these readings were 2 to 3
> degrees of separation.
> 
> This experiment was installed in a manner to make it reversible, so
> as to not damage the gill-vented radiation shield should I want to
> return it to the original configuration.  I used a common white paste 
> gluestick to fasten the 3/4-in wide strips of aluminum foil.
> 
> Kind regards,
> 
> Geoffrey Dick 
> WA4IKQ  / AS140
> Winter Park, FL
> 
> ------------
> > Subject: wxqc Opinions please -- New design for solar radiation shield
> >
> > From: "Bryce Alexander" <bryce at azlab.net>
> > To: <wxqc at lists.gladstonefamily.net>
> > Date: Fri, 4 May 2007 16:54:44 -0700
> > Subject: [wxqc] Opinions please -- New design for solar radiation shielding
> >
> > After reading all the material that the CWOP program references about solar
> > radiation shields I had a brainstorm for a different design. 
> >
> > In essence it is a six inch pipe, open at either end, with the pipe set at
> > an angle such that it is oriented on a North/South plane with the north end
> > higher than the south end. Both ends of the pipe are cut at angles so that
> > no sun is able to enter the bottom half of the pipe regardless of the
> > seasonal angle of the sun's ecliptic. I used nylon screws to mount the
> > instruments to the inside of the pipe to prevent heat transmission from the
> > outside of the pipe through the screws.
> >
> > Take a look at the Flickr images on
> > http://weather.gladstonefamily.net/site/C7166  to see how my prototype is
> > constructed and to make sense of the above description. 
> >
> > The thinking is, that because the north end of the pipe is elevated we will
> > get a chimney effect of the warmer air rising upward at the North end and
> > the cooler air "falling" out the south end of the pipe. The theory is that
> > there is very little chance of air stagnating in this configuration. 
> >
> > One thing I noticed right away is that the temperature and humidity seems
> > much more dynamic (or in other words, more changes during a given time
> > frame) which seems to indicate that I am indeed reducing the incidence of
> > air stagnation I was seeing with a gill style solar shield. 
> >
> > The one down side I see right now is that a driving rain from the North
> > might get the instrument package wet. I will have to create some kind of
> > barrier or hood that will not interfere with the convective flow. The nice
> > thing is that I believe this can remain passive (not fan aspirated) even
> > during the worst of the Arizona heat, we will see this summer.  I do notice
> > some slightly higher temps during the day, but they are not the same thing I
> > was seeing when I had a solar radiation problem. I would attribute that to
> > the microclimate of being between Stucco houses, with cinder block fences
> > and tile roof in proximity to the sensor. 
> >
> > If anyone wants to go back into my historical data I added the shield on
> > April 21 and tweaked my humidity about four days ago. 
> >
> > Let me know what you think, I welcome any suggestions or comments, positive
> > or negative.
> >
> > Feel free to use this design for hobby or research purposes with proper
> > attribution, anything else by permission.
> >
> > ---- 
> >
> > Date: Fri, 4 May 2007 19:45:55 -0500
> > From: "Victor Engel" <brillig at gmail.com>
> > Subject: Re: [wxqc] Opinions please -- New design for solar radiation
> > 	shielding
> >
> > So the thermometer is INSIDE the tube?
> >
> > ----
> >
> > From: "Thomas Giella KN4LF" <kn4lf at earthlink.net>
> > To: "a WXQC e-List" <wxqc at lists.gladstonefamily.net>
> > Date: Fri, 4 May 2007 20:58:45 -0400
> > Subject: Re: [wxqc] Opinions please -- New design for solar radiation
> > 	shielding
> >
> > Hi Bryce,
> >
> > I tried that design 20 years ago and it worked fairly well with forced 
> > aspiration but shortwave radiation and precipitation entry was a problem at 
> > certain times of the year. I ended up using a white plumbing PVC tee and a 
> > couple of 45 degree elbows and that kept shortwave radiation and 
> > precipitation out. For ventilation I used a DC 45 cfm computer type muffin 
> > fan, with the fan sucking fresh air in from the front and passing across the 
> > sensors before reaching the fan. This design worked as good as my louvered 
> > Stevenson Screen.
> >
> > BTW the bottom of the shelter should be 4-5 feet above ground level.
> >
> > Take Care,
> > Thomas Giella, KN4LF
> > Retired Meteorologist
> > Lakeland, FL, USA
> > kn4lf at earthlink.net
> >
> > Lakeland, Florida Daily Climatological Weather Data Archive: 
> > http://www.kn4lf.com/kn4lf22.htm
> > Lakeland, Florida Real Time Weather Observations: 
> > http://www.kn4lf.com/index1.html
> > Harmful Man Induced Climate Change (Global Warming) Refuted: 
> > http://www.kn4lf.com/globalwarminglie.htm
> > FL/US Raw Weather Forecasting Resource Links: 
> > http://www.kn4lf.com/kn4lf13.htm
> > New Scientific Evidence for the Existence of God: 
> > http://www.cosmicfingerprints.com/audio/newevidence.htm
> >
> > After reading all the material that the CWOP program references about solar
> > radiation shields I had a brainstorm for a different design.
> >
> > In essence it is a six inch pipe, open at either end, with the pipe set at
> > an angle such that it is oriented on a North/South plane with the north end
> > higher than the south end. Both ends of the pipe are cut at angles so that
> > no sun is able to enter the bottom half of the pipe regardless of the
> > seasonal angle of the sun's ecliptic. I used nylon screws to mount the
> > instruments to the inside of the pipe to prevent heat transmission from the
> > outside of the pipe through the screws.
> >
> > Take a look at the Flickr images on
> > http://weather.gladstonefamily.net/site/C7166  to see how my prototype is
> > constructed and to make sense of the above description.
> >
> > The thinking is, that because the north end of the pipe is elevated we will
> > get a chimney effect of the warmer air rising upward at the North end and
> > the cooler air "falling" out the south end of the pipe. The theory is that
> > there is very little chance of air stagnating in this configuration.
> >
> > One thing I noticed right away is that the temperature and humidity seems
> > much more dynamic (or in other words, more changes during a given time
> > frame) which seems to indicate that I am indeed reducing the incidence of
> > air stagnation I was seeing with a gill style solar shield.
> >
> > The one down side I see right now is that a driving rain from the North
> > might get the instrument package wet. I will have to create some kind of
> > barrier or hood that will not interfere with the convective flow. The nice
> > thing is that I believe this can remain passive (not fan aspirated) even
> > during the worst of the Arizona heat, we will see this summer.  I do notice
> > some slightly higher temps during the day, but they are not the same thing I
> > was seeing when I had a solar radiation problem. I would attribute that to
> > the microclimate of being between Stucco houses, with cinder block fences
> > and tile roof in proximity to the sensor.
> >
> > If anyone wants to go back into my historical data I added the shield on
> > April 21 and tweaked my humidity about four days ago.
> >
> > Let me know what you think, I welcome any suggestions or comments, positive
> > or negative.
> >
> > ----
> >
> > From: "Bryce Alexander" <bryce at azlab.net>
> > 	<wxqc at lists.gladstonefamily.net>
> > Date: Fri, 4 May 2007 20:59:14 -0700
> > Subject: Re: [wxqc] Opinions please -- New design for solar
> > 	radiationshielding
> >
> > Correct; the humidity and temp sensors are inside the tube.
> >
> > Original Message
> > So the thermometer is INSIDE the tube?
> >
> > ----
> >
> 
=== message truncated ===


Mitch's Automated Weather
http://www.mlmweather.com

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