Re: Is an altimeter useless?

<dold@xxxxxxxxxxxxxxxxxxxxxxxx> wrote in message news:dqh2g9$o67$1@xxxxxxxxxxxxxxxxx
> John R. Copeland <jcopelan@xxxxxxxxxxxxxxxxxxx> wrote:
>> It's conceivable that your barometric pressure fell 0.03 in.Hg in one hour.
>> Do you have a storm approaching?
>> The current weather chart shows a high-pressure center just east of you,
>> and a major storm lying off the Pacific Northwest coast.
>> Ukiah's baro setting has fallen 0.03 inches only over the past 5 hours.
>
> My barometric plot shows 1031.0mb at 1:00pm. The graph looks pretty flat,
> but there is a swell between 10:42 and 11:36 peaking at 1031.4mb. It is
> cloudy today, but not much wind. My LaCrosse weather station has a
> barometer, but doesn't show the pressure, just "up" as the recent trend.
>
> Ukiah would be the closest NWS reporting station.
>
> Does this mean that an altimeter is not useful during changing weather
> conditions?
>
> How often does one need to clibrate the altimeter in static weather
> conditions?
> ---
> Clarence A Dold - Hidden Valley (Lake County) CA USA 38.8,-122.5

The barometric altimeter setting is important in *changing* weather conditions.

Here's the most recent 12 hours worth of baro altimeter settings for Ukiah:
the Date/Time group is ddhhmm in GMT.
"A" signifies altimeter setting in units of 0.01 inches Mercury.
A change of 0.01 corresponds closely to 10 feet of altitude.
Compare these readings to yours, to see if your altitude change corresponds.
If it doesn't, then you're probably also seeing some GPS effects of VDOP.
KUKI 162110Z A3043
KUKI 162056Z A3043
KUKI 162046Z A3043
KUKI 162024Z A3044
KUKI 161956Z A3045
KUKI 161947Z A3045
KUKI 161939Z A3045
KUKI 161929Z A3046
KUKI 161856Z A3047
KUKI 161840Z A3047
KUKI 161756Z A3047
KUKI 161734Z A3047
KUKI 161712Z A3046
KUKI 161656Z A3045
KUKI 161610Z A3044
KUKI 161556Z A3044
KUKI 161545Z A3044
KUKI 161456Z A3042
KUKI 161356Z A3040
KUKI 161256Z A3039
KUKI 161156Z A3040
KUKI 161056Z A3039
KUKI 160956Z A3039

.

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