20
Press the
ALARM
key to reset current value.
Example
: The calibrated pressure sources measure 25.00
inHg. The display console pressure reads 24.85 inHg.
Offset = 25.00 - 24.85 = 0.15 inHg
Note:
The display console displays two different pressures:
absolute (measured) and relative (corrected to sea-level).
To compare pressure conditions from one location to another,
meteorologists correct the pressure to sea-level conditions.
Because the air pressure decreases as you rise in altitude, the
sea-level corrected pressure (the pressure your location would
be at if located at sea-level) is generally higher than your
measured pressure.
Thus, your absolute pressure may read 28.62 inHg (969 mb) at
an altitude of 1000 feet (305 m), but the relative pressure is
30.00 inHg (1016 mb).
The standard sea-level pressure is 29.92 in Hg (1013.2hpa).
This is the average sea-level pressure around the world.
Relative pressure measurements greater than 29.92 inHg
(1013.2hpa)
are
considered
high
pressure
and
relative
pressure measurements less than 29.92 inHg are considered
low pressure.
To determine the relative pressure for your location, locate an
official reporting station near from you (the internet is the best
source for real-time barometer conditions, such as the website
