[wxqc] RE: wxqc Digest, Vol 19, Issue 8

Sun May 7 16:30:08 EDT 2006

I agree with both of the other statements.  I use to pull my hair out about
matching the analysis.  

Rich (4419 - Eagle River, Alaska)

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Today's Topics:

   1. Humidity/Dew Point (James & Julie McNelly)
   2. Re: Humidity/Dew Point (Rich Mulvey)
   3. RE: Humidity/Dew Point (Milford Weather)
   4. Re: Humidity/Dew Point (Hank Sniadoch)

----------------------------------------------------------------------

Message: 1
Date: Sat, 6 May 2006 16:11:26 -0700
From: "James & Julie McNelly" <jjmcnelly at cablespeed.com>
Subject: [wxqc] Humidity/Dew Point
To: <wxqc at lists.gladstonefamily.net>
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What are some things that I can do to get my humidity readings closer to the
analysis readings?  I have put my sensor in a homemade Stevenson Screen and
have it located about 60" above the ground.  My temperatures have stabilized
since adding the screen, but I cannot get the correct humidity readings.  I
am suspecting that it may just be my equipment.  I have a LaCrosse ws-2308.
I am going to aspirate my screen with a solar fan as soon as I get it.  Any
ideas?

James

CW5298

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Message: 2
Date: Sat, 06 May 2006 22:14:15 -0400
From: Rich Mulvey <weather at mulveyfamily.com>
Subject: Re: [wxqc] Humidity/Dew Point
To: Discussion of weather data quality issues
	<wxqc at lists.gladstonefamily.net>
Message-ID: <445D57F7.2070208 at mulveyfamily.com>
Content-Type: text/plain; charset=windows-1252; format=flowed

James & Julie McNelly wrote:
>
> What are some things that I can do to get my humidity readings closer 
> to the analysis readings? I have put my sensor in a homemade Stevenson 
> Screen and have it located about 60 above the ground. My temperatures 
> have stabilized since adding the screen, but I cannot get the correct 
> humidity readings. I am suspecting that it may just be my equipment. I 
> have a LaCrosse ws-2308. I am going to aspirate my screen with a solar 
> fan as soon as I get it. Any ideas?
>

The goal isn't to match the analysis readings - the goal is to have 
accurate data. :-)

You may very well be in a micro-climate in which the humidity readings 
are correct. In my case, for example, I'm in a narrow stream valley, and 
my dewpoint readings are *always* flagged as bad. Nonetheless, they're 
also totally accurate, when I measure independently using a precision 
thermometer and sling psychrometer.

There seems to be a huge amount of concern on the wx list about making 
sure that stations agree with the analysis - and that's simply the wrong 
approach. The analysis is, and will always be, an approximation of 
reality that doesn't necessarily derive correct results for all 
stations. There are just too many potential variables that must be 
accomodated. The analysis is useful to spot trends and flag potential 
problems - but just because it indicates that your readings are bad 
doesn't mean that they're bad. To determine that, you need independent 
confirmation of the values you generate.

- Rich

------------------------------

Message: 3
Date: Sun, 7 May 2006 10:54:41 -0400
From: "Milford Weather" <Weather at pdfamily.com>
Subject: RE: [wxqc] Humidity/Dew Point
To: "'Discussion of weather data quality issues'"
	<wxqc at lists.gladstonefamily.net>
Message-ID: <200605071454.k47EsfR12047 at plus41.host4u.net>
Content-Type: text/plain; charset="us-ascii"

I have to agree with Rich; the goal is to report accurate readings for your
location.  On calm nights I frequently get a temperature bump around 4am
that I do not see on any other station in my area.  I live on the side of a
hill and attribute it to the cold air settling into the valley and forcing
the warmer air upward.  I have spent a career of engineering and calibration
and maintain my station as accurately as possible so the results are
accurate and true.  If that is done by each of us, the data will be a true
representation of the conditions at our own locations, which is what I see
as the goal.

Paul

CW3414

Weather Spotter

 <http://mysite.verizon.net/vzeo4iq2/> http://www.PDfamily.com/weather
<http://www.pdfamily.com/weather/> 

The goal isn't to match the analysis readings - the goal is to have 

accurate data. :-)

You may very well be in a micro-climate in which the humidity readings 

are correct. In my case, for example, I'm in a narrow stream valley, and 

my dewpoint readings are *always* flagged as bad. Nonetheless, they're 

also totally accurate, when I measure independently using a precision 

thermometer and sling psychrometer.

There seems to be a huge amount of concern on the wx list about making 

sure that stations agree with the analysis - and that's simply the wrong 

approach. The analysis is, and will always be, an approximation of 

reality that doesn't necessarily derive correct results for all 

stations. There are just too many potential variables that must be 

accomodated. The analysis is useful to spot trends and flag potential 

problems - but just because it indicates that your readings are bad 

doesn't mean that they're bad. To determine that, you need independent 

confirmation of the values you generate.

- Rich

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Message: 4
Date: Sun, 07 May 2006 11:43:33 -0400
From: Hank Sniadoch <sniadoch at frontiernet.net>
Subject: Re: [wxqc] Humidity/Dew Point
To: Discussion of weather data quality issues
	<wxqc at lists.gladstonefamily.net>
Message-ID: <445E15A5.4030108 at frontiernet.net>
Content-Type: text/plain; charset="iso-8859-1"

That's why I don't change my readings to agree with the analysis.  My 
station(s) are at 1400 ft and typically I get cold air settling .... 
last night I matched the coldest readings in NY but I know my readings 
are accurate since I calibrate my stations with thermometers (I have 2) 
that are calibrated and accurate to within 0.1 degrees .... (cost $300 
each) .... sometimes I'm 10-15 degrees colder than a mountaintop 3-4 
miles away from me .... I can't believe microclimates !!!!

Milford Weather wrote:

> I have to agree with Rich; the goal is to report accurate readings for 
> /your/ location.  On calm nights I frequently get a temperature bump 
> around 4am that I do not see on any other station in my area.  I live 
> on the side of a hill and attribute it to the cold air settling into 
> the valley and forcing the warmer air upward.  I have spent a career 
> of engineering and calibration and maintain my station as accurately 
> as possible so the results are accurate and true.  If that is done by 
> each of us, the data will be a true representation of the conditions 
> at our own locations, which is what I see as the goal.
>
>  
>
> Paul
>
>  
>
> CW3414
>
> Weather Spotter
>
> http://www.PDfamily.com/weather <http://www.pdfamily.com/weather/>
>
>  
>
> The goal isn't to match the analysis readings - the goal is to have
>
> accurate data. :-)
>
>  
>
> You may very well be in a micro-climate in which the humidity readings
>
> are correct. In my case, for example, I'm in a narrow stream valley, and
>
> my dewpoint readings are *always* flagged as bad. Nonetheless, they're
>
> also totally accurate, when I measure independently using a precision
>
> thermometer and sling psychrometer.
>
>  
>
> There seems to be a huge amount of concern on the wx list about making
>
> sure that stations agree with the analysis - and that's simply the wrong
>
> approach. The analysis is, and will always be, an approximation of
>
> reality that doesn't necessarily derive correct results for all
>
> stations. There are just too many potential variables that must be
>
> accomodated. The analysis is useful to spot trends and flag potential
>
> problems - but just because it indicates that your readings are bad
>
> doesn't mean that they're bad. To determine that, you need independent
>
> confirmation of the values you generate.
>
>  
>
> - Rich
>
>  
>
>  
>
>  
>
> _______________________________________________
>
> wxqc mailing list
>
> wxqc at lists.gladstonefamily.net
>
> http://pond1.gladstonefamily.net:8080/mailman/listinfo/wxqc
>
>  
>
> The contents of this message are the responsibility of the author.
>
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End of wxqc Digest, Vol 19, Issue 8
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