Yes, aircraft altimeters are adjustable.  The dial that you set the
altimeter setting with is called the Kollsman window.  I got
sidetracked last evening, didn't make it over to the hangar, but have
to go there tonight.

Regards,
Bob

On 6/1/05, Bill & Pookie <reddx@comcast.net> wrote:
> The gentleman who was going to look at his altimeter in his plane may have
> the best information.  I assume that the instrument would be adjustable to
> any pressure at any airport prior to starting a flight.  So the range of
> adjustment would cover all "flying" weather.
> 
> Bill
> 
> ----- Original Message -----
> From: "Peter" <plp@actcom.co.il>
> To: "Microcontroller discussion list - Public." <piclist@mit.edu>
> Sent: Wednesday, June 01, 2005 6:58 AM
> Subject: Re: [EE] Atmospheric Pressure Ranges
> 
> 
> >
> > On Tue, 31 May 2005, Mike Hord wrote:
> >
> > > I'm trying to get a feel for the "normal" range of atmospheric
> > > pressure.
> > >
> > > Wikipedia tells me that the highest and lowest ever recorded
> > > barometric pressures are 108.57 kPa and 86.996 kPa,
> > > respectively.  It also tells me that "standard" atmospheric
> > > pressure is 101.325 kPa.  What it does NOT tell me (nor
> > > does anywhere else) is what the "normal" range is; that is,
> > > if a good, strong thunderstorm passes through, what can
> > > I expect the pressure to be?  Likewise, in a typical high
> > > pressure area, what can I expect the pressure to be?
> >
> > It depends at what altitude you are.
> >
> > > I'm trying to develop a water depth gauge, and if possible,
> > > I'd like to get some feel for the variation of pressure based
> > > on atmospheric variations.  The highest to lowest cited
> > > above would represent a 2.2 meter(!) fluctuation in the
> > > depth of a body of water, if one were basing the depth on
> > > the pressure at the bottom.  Needless to say, that
> > > kind of variation would render the information useless.
> >
> > Pressure based depth gauges use a differential transducer. One end is
> > exposed to the air. This removes the problem you describe and adds the
> > problem of having two tube openings to keep clean.
> >
> > > Normal diurnal cycles are <.5 kPa, which corresponds
> > > to approximately 5 cm of water depth.  No info on
> > > typical changes outside those variations, however.
> > >
> > > Differential measurement is NOT an option for this
> > > application.
> >
> > You can measure depth pretty accurately using ultrasound from below. The
> > water/air interface bounces it back strongly. But if you have waves it
> > will be hard anyway.
> >
> > Peter
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