[wxqc] Opinions please -- New design for solarradiationshielding

Sat May 5 16:08:48 CDT 2007

It seems that wrapping in shiny foil would reduce solar gain, which would
reduce the convection, which would defeat the purpose of the "chimney"  The
design is inherently flawed.  Any chimney effect is the direct result of
overheating the air, which is exactly what you're trying to avoid.  

Google for enclosure designs, and pick from there.  This isn't rocket
science.

-----Original Message-----
From: wxqc-bounces at lists.gladstonefamily.net
[mailto:wxqc-bounces at lists.gladstonefamily.net] On Behalf Of Geoffrey Dick
Sent: Saturday, May 05, 2007 13:55
To: wxqc at lists.gladstonefamily.net
Subject: Re: [wxqc] Opinions please -- New design for
solarradiationshielding

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.
>
> ----
>
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