Davis Instruments Weather Club
August 2000
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Here's a quick preview of this month's contents:
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Positioning your weather station...Editing vs. inserting weather data
...Weather observation times world 'round... Enjoy!
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Davis: Positioning your weather station
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Our tech support and customer service staff are frequently asked, "What's
the best place to install my weather station? How will the installation
location affect my readings?"
For most of us, there is no ideal place to install a weather station. We
make compromises based on where we live and what's around us. But that
doesn't mean we can't get good weather information!
Take a look around your house. Is there a location that's clear of trees,
walls or other obstructions? For many people, the roof fits the bill. We
suggest placing the anemometer 8 feet (2.5 m) above the peak of the roof .
At this height, the wind speed measurement will not be affected by lift —
or wind coming up from the roof. What happens if you can only get 3 feet (1
m) above the peak? Your wind speed accuracy may drop by 2-4%.
Will strapping a Wireless or EZ-Mount station to a chimney or television
antenna affect readings? If you use your fireplace and chimney, install your
weather station somewhere else. Smoke from the fireplace carries particles
that can get trapped in the sensors. Additionally, warm air exiting the
flue may give you a false temperature reading. A television antenna won't
affect readings. You just need to be sure it is sturdy enough to support the
weather station sensors. If there are transmitting antennae nearby, you may
notice some RF (Radio Frequency) interference. RF can be minimized by
installing a Protected Junction Box or attaching Torried Core around the
cables.
Those of us who prefer to keep our feet — and our station — firmly planted
on the ground need to find an unobstructed part of the yard. The anemometer
extension pole, included with the mounting tripod, raises the anemometer
above the fence line. This will give you a more accurate wind reading. The
rain collector can be mounted on a post, pole, or even the ground. Just be
sure it's in an open area -- not under trees or beside a building.
Temperature sensors housed in radiation shields can be out in the yard,
while unprotected temperature sensors should be in a sheltered, airy place
protected from sun and rain. Be sure to give your temperature sensor room
to breath. It gets pretty warm under the eaves, and the buildup of radiant
heat will result in high temperature readings.
With careful planning, you can collect accurate weather data.
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Tech Tip: WeatherLink Software -- Edit vs. insert
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A bunch of you responded to last month's e-news saying that we still hadn't
addressed the issue of inserting weather data into WeatherLink. Well, you
were right.
As we all know by now, you can edit data collected by WeatherLink. One
reader asked why anyone would want to. Let's suppose your station is
working just fine — except that a pair of robins is nesting in your rain
collector. As a storm passes through, the birds hunker down blocking off
the rain collector. After the storm, you check your data and see that no
rainfall was recorded. Using WeatherLink's edit function, you can enter the
storm's rainfall total after the fact.
But say that same storm comes through and you have a power outage. You
haven't changed your backup battery since who knows when, so your station
loses power too. There would be no data recorded, so there would be no
records to edit. What then?
Unfortunately you are out of luck. The current software can't support
inserting new records. While we're looking into ways to solve this dilemma,
you might want to replace your backup battery!
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Reader's Write: Weather observation times world 'round
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We look forward to your e-mails after each month's newsletter goes out.
Many of you share bits of information that become part of the next month's
newsletter. Others send us a question that piques our curiosity. Thanks
for all your responses, and please keep sending them!
This month we heard from Charles in the UK. He wrote with an interesting
observation and posed a question as well.
>I see that the Davis monthly report records daily data for the period from
midnight to midnight. Here in Britain all observations are made at 9.00AM
(10.00AM in British summer time) so Davis's daily observations are not
comparable with anyone else's.
>When do people in the US and other countries make observations?
What a great question Charles! According to the "Future of the National
Weather Service Cooperative Observer Network":
>Monthly average temperatures in the United States are computed using daily
maximum and minimum temperatures. For climatological purposes, the
preferred measurement period is midnight-to-midnight. However, because
readings by human observers at midnight are not feasible for a "volunteer"
network, the vast majority of cooperative observers operate on a
"climatological day" that does not correspond to the standard
midnight-to-midnight calendar day.
This means our stations record based on the US preferred measurement period.
It still doesn't answer the question of what time people make
observations. And we weren't able to find any information about a world
standard for taking weather readings. So weather observers, what time do
you take your readings and why?
Watch for the answers in next month's newsletter!
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That's it for August's news. See you next month! To subscribe to this e-newsletter go to: http://davisnet.com/news/e_club_signup.asp
