[wxqc] Weather station questions

Tue Apr 4 21:35:12 EDT 2006

Hi,

Gary is correct about the temperature accuracy of the LaCrosse 23xx 
stations.  CWOP QC statistics have shown numerous cases  where the temp 
sensor has a significant warm bias during maximum solar radiation.  The 
trouble is the surplus "Leggs" cone LaCrosse passes off as a radiation 
shield (they probably got a great deal for the cones on EBay from my 
ex-wife who collected them for no particular reason, why knew?).  The 
biggest problem is a lack of ventilation, see here 
http://www.lacrossetechnology.com/products/pwc/sensors/2315al_thermo.html, 
so as the cone is heated by the sun, the heat within the cone collects 
causing temperatures to reported 10-20 degrees above the actual ambient 
afternoon temperature.

The good news is you can build a "home brew" radiation shield which have 
louvers which supports sampling of the free "ambient" air.  I recommend 
everyone using the stock LaCrosse "cone" on the temperature sensor to 
visit Russ Chadwick's Radiation Shield page, 
http://www.wxqa.com/shields.html, and consider replacing it with one of 
the examples discussed on the page.

On a positive note, I'd love to add your weather code to the CWOP Info 
page, http://www.cwop.info.  What "CW" ID are you?

Dave
CW0351

Shell Shrader wrote:

> heh... my La Crosse 2315-11 is more accurate than our local 
> "Meteorologist".  Granted, wireless mode updates only come in once 
> every 90 or so seconds... wired you should expect an update about once 
> every 45 seconds.
>  
> I've also hacked (with the help of a bunch of Europeans) the protocol 
> and went public with a communications library for those with 
> programming knowledge... all free of course.
>  
> http://weather.shellware.com/
>
> ------------------------------------------------------------------------
> *From:* Gary Oldham
> *Sent:* Fri 3/31/2006 8:13 PM
> *To:* 'Discussion of weather data quality issues'
> *Subject:* RE: [wxqc] Weather station questions
>
> There are several lower cost options.  Some La Crosse stations are 
> under $200 USD, but have connectivity issues, accuracy concerns, and 
> update far less frequently than other lower end stations such as the 
> Oregon Scientific line.  You may want to look into 1-Wire systems, 
> which can be built modularly, adding on sensors as you wish.  Weather 
> Display software (http://www.weather-display.com/) supports one wire 
> components, and I believe there is 1-wire software for them as well, 
> though far less full featured than is Weather Display.  One good 
> source for 1-wire components is http://www.hobby-boards.com/.
>  
> Gary
> CW0146
>
> ------------------------------------------------------------------------
> *From:* wxqc-bounces at lists.gladstonefamily.net 
> [mailto:wxqc-bounces at lists.gladstonefamily.net] *On Behalf Of *Wayne 
> Sellin
> *Sent:* Friday, March 31, 2006 12:22 PM
> *To:* Discussion of weather data quality issues
> *Subject:* Re: [wxqc] Weather station questions
>
> Does anyone know of less frills weather stations? I would like to 
> Build a wind speed indicator and not pay so much money.
> Wayne
> KG4FRL
>
>     ----- Original Message -----
>     *From:* Ken Whelan <mailto:ken at ubh.com>
>     *To:* wxqc at lists.gladstonefamily.net
>     <mailto:wxqc at lists.gladstonefamily.net>
>     *Sent:* Tuesday, March 28, 2006 2:21 PM
>     *Subject:* [wxqc] Weather station questions
>
>     Is there an archive of this list that I can search ?   I don't
>     normally join a list and immediatly post to it without first
>     reading some of the messages,  however,  I've got some questions I
>     bet you can help me with.
>      
>     I've just setup a new Weather station,  It is a Davis Vantage Pro
>     II.   I live on Beaver Lake in NW Arkansas.    I have placed the
>     weather station about 20 foot in the air off from my dock.  
>     Comparing the readings to other stations in the area,  things look
>     very close most of the time,   however,  When the wind is calm, 
>     the evaporation from the lake raises the humidity in the whole
>     valley,  its not just the sensor on my dock,   I had the ISS up at
>     my house for a day or two and it reads high when it is up there as
>     well.
>      
>     I would not be surprised if MADIS kicks out my dew point temp
>     because my humidity reading is different than the rest of the area
>     some of the time.   I guess this is called a Microclimate or
>     something along those lines.   How is that normally handled and is
>     it something I should be worried about ?  
>      
>     I also have a lake temperature sensor as well.   I'm thinking some
>     of my fishing buddies might find this useful.
>      
>     kw
>
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