pressure
- From: "Stuart" <member@xxxxxxxxxxxxxxxxxxxx>
- Date: Fri, 29 Apr 2005 21:26:44 +0100
I wonder if someone here can help me. Ive just bought a very nice Suunto
Observer watch which is great and gadgety and does altimeter readings,
compass readings temperature, barometric readings and even tells the time.
Ive looked around the net, and read the instruction manual for the watch
loads of times, but cannot find the answers to my searching questions.
I went to my local beach and set the altimeter to zero. This apparently
automatically sets the sea level pressure in the watch also. The watch
displays in big bold type the current sea level pressure, which obviously
rises or falls. Underneath this, in smaller type, the watch displays
current atmospheric pressure which also rises or falls. My question is that
the atmospheric pressure is always 5 digits behind the sea level pressure,
always. The sea level pressure is currently recorded on the watch as 1015,
and the atmospheric pressure at 1010, 5 behind again. Is this always the
case or should it fluctuate a bit?
Also, fair enough the watch can say what the current atmospheric pressure
is, because it has a sensor, but how can it know what the sea level pressure
is if its not at sea level?
Also, as a rule of thumb, how much does pressure need to rise or fall in a 3
hour period to give a strong indication of changing weather?
It fell today (Cornwall UK) by about 20 hPa, which would seem to me to be a
big drop, but the weather just turned from cloudy and dry to cloudy and a
bit drizzly. I think I half expected such a big fall in pressure to
indicate at least a hurricane, but maybe 20 hPa isnt a big fall in your
eyes?
Sorry to ramble on, but I do find all this very interesting.
Thanks for any help,
CHEERS
Stuart
.
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