Absolute air pressure is measured constantly
Absolute air pressure + Reference altitude = Sea level air pressure (BAROMETER profile)
Absolute air pressure + Reference altitude = Altitude (ALTIMETER profile) Changes in local weather conditions will affect altitude readings. If local weather changes often, it is advisable to frequently reset the local reference altitude value, preferably before starting your journey and when an altitude reference value is available. If local weather is stable, the local altitude reference value can be set just once a day.
6.1.3 Getting incorrect readings
ALTIMETER + standing still + weather change
If you use the ALTIMETER profile for a longer period of time without any elevation change and the weather changes, then your Suunto Lumi reads the weather changes as altitude changes.
ALTIMETER + altitude moving + weather change
If the weather is frequently changing as you are either ascending or descending, your Suunto Lumi will give incorrect readings.
BAROMETER + altitude moving
If you use the BAROMETER profile for a longer period of time as you are either ascending or descending, your Suunto Lumi assumes you are standing still and reads your altitude changes as weather changes.
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