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

Sat May 5 15:55:02 CDT 2007

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?
>
> ----
>
> Date: Sat, 05 May 2007 10:45:02 -0400
> From: Philip Gladstone <philip at gladstonefamily.net>
> Subject: Re: [wxqc] Opinions please -- New design for solar
> 	radiation	shielding
>
> Thomas Giella KN4LF wrote:
> > 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.
>   
> I am now using a similar design -- an inverted J made out of PVC with a 
> muffin fan. See the pictures on 
> http://weather.gladstonefamily.net/site/C0003
>
> Philip
>
> ----
>
> From: "Bryce Alexander" <bryce at azlab.net>
> 	<wxqc at lists.gladstonefamily.net>
> Date: Sat, 5 May 2007 08:03:34 -0700
> Subject: Re: [wxqc] Opinions please -- New design for
> 	solarradiation	shielding
>
> I had seriously considered using something similar to yours, but I am trying
> to come up with something that is passive, even in Arizona, rather than run
> power to the fan for aspiration. What makes my design unique is that by
> placing it at an angle (similar to the angle of a solar panel) the
> convective nature of the air will self aspirate the tube. An inverted J
> design will trap warm air at the top and absolutely require fan aspiration.
> What makes this angled design unique is that it shouldn't require the fan.
>
> The fact that it is a tube is only a small part of the overall design.
>
> ----
>