Hello Ian.
Having been a professional meteorologist for over 30 years years, I
feel obliged to stop list lurking and give you an appropriate answer.
When you remove the batteries, you do not need to worry. The barometer
reading will be OK immediately after you put them back in. The
pressure tendency (i.e. the change) might be lost, but will be
suitable for a weather prediction after a few hours. But I don't trust
my own digital weather station (Davis) too much for its forecast, the
prediction of the national weather centre (where my former colleagues
are working) is much better of course ;-)
About the pressure-altitude calibration: this should be made indeed
when you are 500m above sea level. Even when you live in a highrise
building this is necessary. All air pressure reports (also of the town
you are mentioning) are corrected to sea level reading - otherwise
they would be worthless for synoptic meteorology.
Therefore the fact that the nearby weather stion is 100m lower than
your position is not relevant: you both should have the same sea level
pressure reading.
You can trust the reading of that more or less nearby town when you
pick a day with little pressure gradient - which means that you should
look at all readings available in Switzerland (or Central Europe) and
make your correction on a day which shows little difference between
those individual readings. Or you could call your weather centre or a
nearby airfield and ask what the correct pressure for your location
would be. They will certainly be able to tell you!
The question whether you need to know the exact air pressure I cannot
answer for you... Most people who own a weather station obviously
think so...
BTW, where exactly are you located, and which brand of weather station
do you own? Maybe I can help from here (Netherlands)
Good luck,
Frank van Lindert
Utrecht NL
On Tue, 11 Dec 2007 10:15:04 +0100, you wrote:
>I don't consider myself unintelligent, but playing with my digital
>weather station is making me doubt my abilities ;-)
>
>firstly do I need to be concerned that I lose the current barometric
>setting when I remove the batteries (so that it can see the external
>temperature sensor when its batteries have been changed). I think the
>weather prediction is done on change rather than values, also do I need
>to be concerned that I haven't calibrated it for 500m above sea level
>and just leave it at the default.
>
>I believe there are some online sites which give barometric pressure but
>I didn't find one for the small swiss village where I live only the
>nearest town which is 100m lower in altitude, do these things matter in
>the scheme of things i.e is it worth the effort, do I really need to
>know the exact barometric pressure?
>
>Iechyd Da!
>Ian
>
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