[pct-l] how an altimeter works, take 2

[Romano Scaturro]

Since this subject has come up.....how is barometric pressure measured?


----- Original Message ----- 
From: "Postholer" <public at postholer.com>
To: <pct-l at backcountry.net>
Cc: <littleleum at yahoo.com>
Sent: Tuesday, March 03, 2009 10:14 PM
Subject: [pct-l] how an altimeter works, take 2


>> The question remains though, how does the watch supposedly determine
>> which pressure change is due to elevation and which pressure change is
>> due to changes in weather?
>
> It doesn't. It senses a change in barometer regardless if caused by
> barometric or altitude change. The natural change in barometric pressure 
> is
> what causes your altimeter to become inaccurate, that is why you need to
> reset the elevation against a known altitude periodically.
>
> -postholer
>
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