Davis Instruments Weather Club
May 2000
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Here's a quick preview of this month's contents:
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A sailing club's weather data is up a tree on an island...Planning ahead
makes installation easy...Help for editing archived weather data...Enjoy!
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Cool Ap: A Weather Station up a tree on an island?
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What is the most unusual weather station installation you can imagine?
Would you believe a station in a tree?
This month we travel to Lake Paijanne, the second largest lake in Finland.
The Pohjois-Paijanteen Pursise Sailing Club is located on an island about 30
km south of Jyvaskylad in Lake Paijanne. They use a Weather Monitor II to
track weather on the lake. In order to get good wind readings, the club
installed an anemometer at the top of a fir tree. Check out the photo at
http://www.pppursiseura.fi/cgi-bin/photoalbum.cgi?Album=&NC=1&NR=1&StartPic=
../kuvat//0731_008.jpg. The climb to the top of the tree looks a little
scary to us, but for a sailor, maybe it's no different than clambering up a
sailboat mast!
Illka Lilja, our distributor in Finland, assures us that the installation
works just fine. The Weather Monitor II data is available to club members
via their cell phones. Members call up the station to request data. The
Linux system checks its ISDN modem confirming the caller's a club member.
Once membership is confirmed, the weather data is sent as a text message.
Pretty cool!
Thanks for the picture, Illka. If you have a cool installation or weather
station application, we'd like to hear from you too. Just reply to the
newsletter and tell us your story. Who knows...we might be reading about
you next!
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Tech Tip: Planning ahead makes installation easy
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The warm weather is here, and that means it's weather station installation
time. Are you thinking about scaling the rooftop and installing your
sensors? Before you go, we'd like to share some tips that should make the
job a little easier.
1. Make sure your sensors are working properly while you're still inside.
Plug the sensors into the junction box and check for readings on your
display console. Be sure to spin the wind cups and move the wind vane. One
common mistake is plugging the sensors into the wrong spot on the junction
box.
2. Decide where you're placing the sensors and make sure you've got enough
cable. The anemometer, rain collector and temperature sensor don't have to
be next to each other. So how far can each sensor be from the weather
station? Here are some guidelines to help you plan your Weather Wizard III
or Weather Monitor II installation.
The Rain Collector's maximum cable run is 900' (270 m). This length is
measured from the rain collector to the display console.
The Temperature Sensor and Probe both have maximum cable runs of 300' (91
m). The distance is from the sensor to the console.
Staying within the maximum cable lengths ensures the accuracy of your rain
and temperature data. Going beyond the max can result in bad readings or no
readings at all.
Determining the maximum cable length for the anemometer is a little
trickier. The maximum wind speed reading decreases as the cable length
increases. The cable is measured from the anemometer to the console. At
140' (42 m), the maximum wind speed is 175 mph (78 m/s). At 240' (73 m),
the maximum is 140 mph (62 m/s). At 340' (103 m), the maximum drops to 70
mph (31 m/s). The accuracy of the readings below the maximum wind speed is
not affected.
What does this mean to you? If maximum wind speeds are relatively low where
you live, you can place your anemometer further away than someone who lives
in hurricane country. If the wind speed does exceed the maximum for the
cable length you've installed, your weather station will show no wind or a
very low reading.
GroWeather and Health and Energy EnviroMonitors have slightly different
maximum cable runs. Refer to the table on page 22 of our catalog or check
out the sensor and cable specification sheets under support.
http://www.davisnet.com/support/weather/support_docs.asp?dtype=2.
3. Last but not least -- be careful and take your time. If you have
problems, you can contact tech support Monday through Friday from 7 a.m -
5:30 p.m. Pacific Time.
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Reader's Write: A request for help editing archived weather data.
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It's been a while since we've shared a club member's request. Past
requests, such as how to keep birds away from rain collectors, have launched
fun and informative discussions. We hope this request from Roger in
Michigan will continue the tradition. Roger writes:
>I need a program that will let me edit the archived monthly weather data.
I don't really have the expertise to write anything myself, but I thought
with all the users you have that someone may have written a program to edit
past data in some more efficient way than one record at a time.
>What I'm trying to accomplish is to generally add data that was lost due to
a power problem or other mishap when I have lost data. What I'd like to do
is just duplicate yesterday's data and make it today's. While it may not
be totally accurate, it's better than having chunks of missing data.
>Is there a place in the Weather Club where someone can make a request like
this? I'm not really interested in paying for special programming, but
thought maybe someone may have created such an program.
Here's your request Roger! Is anyone using a program that will help? We'll
share the answers in next month's newsletter.
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