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<DIV><SPAN class=178294922-01042005><FONT face=Arial color=#0000ff
size=2>Actually, that's what's in the AAG humidity sensor. Supposedly, it's also
used for medical applications <A
href="http://content.honeywell.com/sensing/prodinfo/humiditymoisture/technical/faq_hummoisture.stm">http://content.honeywell.com/sensing/prodinfo/humiditymoisture/technical/faq_hummoisture.stm</A> .
What I've done is taken a piece of 2 inch white PVC. On the upper end, there's a
2 to 3 inch adapter with a 12 volt fan siliconed into the opening.
There's two 90 degree bends, the other end of which attaches to about a
foot of 2 inch pipe - think candy cane with a fan on the short end. The
humidity, and pressure sensors are in this pipe. This whole assembly responds
very quickly to temp and humidity changes - <A
href="http://www.findu.com/cgi-bin/wxpage.cgi?call=cw3321&last=6">http://www.findu.com/cgi-bin/wxpage.cgi?call=cw3321&last=6</A>,
and seems immune to direct sun. </FONT></SPAN></DIV>
<DIV><SPAN class=178294922-01042005><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=178294922-01042005><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=178294922-01042005><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV></DIV>
<DIV><FONT face=Tahoma size=2>-----Original Message-----<BR><B>From:</B>
wxqc-bounces@lists.gladstonefamily.net
[mailto:wxqc-bounces@lists.gladstonefamily.net] <B>On Behalf Of </B>Sandy and
David Helms<BR><B>Sent:</B> Friday, April 01, 2005 7:27 AM<BR><B>To:</B>
Discussion of data quality issues<BR><B>Subject:</B> RE: [wxqc] Fog, Dew Point,
and RH<BR><BR></DIV></FONT>
<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px">
<DIV><SPAN class=388592212-01042005><FONT face=Arial color=#0000ff size=2>I
want one. Them sell 'em at Walmart? Maybe Honeywell got those stats in
their test chamber for the sensor, but in your backyard
YMMV.</FONT></SPAN></DIV>
<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px">
<DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma
size=2>-----Original Message-----<BR><B>From:</B>
wxqc-bounces@lists.gladstonefamily.net
[mailto:wxqc-bounces@lists.gladstonefamily.net]<B>On Behalf Of
</B>Bob<BR><B>Sent:</B> Friday, April 01, 2005 7:14 AM<BR><B>To:</B>
'Discussion of data quality issues'<BR><B>Subject:</B> RE: [wxqc] Fog, Dew
Point, and RH<BR><BR></FONT></DIV>
<DIV><SPAN class=244041312-01042005><FONT face=Arial color=#0000ff
size=2>Here's the data on the sensor. <A
href="http://content.honeywell.com/sensing/prodinfo/humiditymoisture/009012_2.pdf">http://content.honeywell.com/sensing/prodinfo/humiditymoisture/009012_2.pdf</A></FONT></SPAN></DIV>
<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px">
<DIV></DIV>
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left><FONT
face=Tahoma size=2>-----Original Message-----<BR><B>From:</B>
wxqc-bounces@lists.gladstonefamily.net
[mailto:wxqc-bounces@lists.gladstonefamily.net] <B>On Behalf Of </B>Sandy
and David Helms<BR><B>Sent:</B> Friday, April 01, 2005 12:19
AM<BR><B>To:</B> Discussion of data quality issues<BR><B>Subject:</B> RE:
[wxqc] Fog, Dew Point, and RH<BR><BR></FONT></DIV>
<DIV><SPAN class=845295904-01042005><FONT face=Arial color=#0000ff
size=2>Yep, the fog you describe should give you 100% RH (temp and
dew point same) nearly every time. But, having fog doesn't mean you
will have 100% RH. Sometimes there is a small layer near the surface
that is not quite saturated yet the horizontal visibility can be very
low. Its an old rule of thumb that you never code fog in
an aviation weather (METAR) observation with dew point depression greater
than 7 F (quiz for tonight, who knows what an AXXX bulletin is?), which is
to say, you can get fog with temp/dew point depressions anywhere from
0 to 7 F degrees. </FONT></SPAN></DIV>
<DIV><SPAN class=845295904-01042005><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=845295904-01042005><FONT face=Arial color=#0000ff
size=2>On the Honeywell accuracy of 2%, I'm a bit skeptical. That
kind of accuracy is typically reached by research quality
hygrometers. I think most sensor manufacturers won't claim
accuracies better than 5%, and that is a stretch as most hygrometer's
performance will "drift" (degrade) over time. </FONT></SPAN></DIV>
<DIV><SPAN class=845295904-01042005><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=845295904-01042005><FONT face=Arial color=#0000ff
size=2>Looking over your station reports, you track very well with KILM
with temp and dew point so you are doing very well.</FONT></SPAN></DIV>
<DIV><SPAN class=845295904-01042005><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=845295904-01042005><FONT face=Arial color=#0000ff
size=2>DaveH</FONT></SPAN></DIV>
<DIV><SPAN class=845295904-01042005><FONT face=Arial color=#0000ff
size=2>CW0351</FONT></SPAN></DIV>
<DIV><FONT face=Tahoma><FONT size=2><SPAN class=845295904-01042005><FONT
face=Arial color=#0000ff></FONT></SPAN></FONT> </DIV>
<DIV><FONT size=2><SPAN
class=845295904-01042005> </SPAN>-----Original
Message-----<BR><B>From:</B> wxqc-bounces@lists.gladstonefamily.net
[mailto:wxqc-bounces@lists.gladstonefamily.net]<B>On Behalf Of
</B>Bob<BR><B>Sent:</B> Thursday, March 31, 2005 10:23 PM<BR><B>To:</B>
wxqc@lists.gladstonefamily.net<BR><B>Subject:</B> [wxqc] Fog, Dew Point,
and RH<BR><BR></DIV></FONT></FONT>
<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px">
<DIV><SPAN class=164475802-01042005><FONT face=Arial size=2>If we are in
a heavy fog, am I incorrect in believing that the RH is 100%? As I look
at my QC data for Today, I note that I am supposedly in error from 05:00
- 10:00 for reporting a dew point pretty close to ambient
temperature - ie; 100% humidity. During that time period, the entire
area, including the weather service was under an extremely dense fog. <A
href="http://weather.gladstonefamily.net/cgi-bin/wxqchart.pl?date=20050401&site=C3321">http://weather.gladstonefamily.net/cgi-bin/wxqchart.pl?date=20050401&site=C3321</A></FONT></SPAN></DIV>
<DIV><SPAN class=164475802-01042005><FONT face=Arial size=2>And the
surrounding stations are reporting similar data....</FONT></SPAN></DIV>
<DIV><SPAN class=164475802-01042005><FONT face=Arial size=2><A
href="http://www.srh.noaa.gov/data/obhistory/KILM.html">http://www.srh.noaa.gov/data/obhistory/KILM.html</A></FONT></SPAN></DIV>
<DIV><SPAN class=164475802-01042005><FONT face=Arial size=2><A
href="http://www.srh.noaa.gov/data/obhistory/KLBT.html">http://www.srh.noaa.gov/data/obhistory/KLBT.html</A></FONT></SPAN></DIV>
<DIV><SPAN class=164475802-01042005><FONT face=Arial size=2><A
href="http://www.srh.noaa.gov/data/obhistory/KFAY.html">http://www.srh.noaa.gov/data/obhistory/KFAY.html</A></FONT></SPAN></DIV>
<DIV><SPAN class=164475802-01042005><FONT face=Arial
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=164475802-01042005><FONT face=Arial size=2>I have three
temperature sensors, and a Honeywell HIH 3610 humidity sensor in a
fan aspirated tube with an intake 5 feet off the grass. The temperature
sensors all read within .2 degrees F, and previously been verified
accurate accurate within .3 degrees F at 32 F, and 212 F, I'm not likely
to be reporting incorrect temperature. The Honeywell humidity
sensor has a claimed accuracy of 2% Rh. </FONT></SPAN></DIV>
<DIV><SPAN class=164475802-01042005><FONT face=Arial
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=164475802-01042005><FONT face=Arial size=2>SO..... If
we are experiencing "can't see two feet in front of you" fog, should I
not be reporting ambient temp =
RH?</FONT></SPAN></DIV></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BODY></HTML>