ALTIMETER AND BAROMETER DETAILS
Effects of Atmospheric Pressure Changes.
A change in atmos-
pheric pressure will make the displayed altitude different from the
known altitude of a landmark. The ST 4000 can be adjusted so that
it displays the same altitude as the landmark. Minor atmospheric
pressure changes may cause the displayed altitude to vary from the
actual altitude by 50 feet. With the arrival or departure of a weather
front, displayed altitude can change 100 to 200 feet, and a storm can
cause a change of more than 200 feet. Wind, rain, snow, and humidity
do not affect altimeter readings.
Barometer-Altimeter Synchronization.
Synchronization (the relation
between altitude and sea level barometer) is set at the factory. To
ensure barometer accuracy you can check it after a year or two and
correct minor drift if necessary. You must know your current altitude
and must get the current sea level barometer from a local airport or
weather broadcast to make this adjustment.
You can also synchronize the thermometer if it reads consistently
high or low over a range of temperatures.
Thermometer Accuracy.
The ST 4000 measures the ambient air tem-
perature with a sensor inside its case. When the watch is worn
against your skin, temperature readings will be affected significant-
ly. Direct sunlight can also cause the ST 4000 to give high readings.
For accurate readings, remove the watch from your wrist and place
away from direct sunlight.
Display.
The Altimeter and Thermometer revert to the Clock 10 minutes
after the last time a button is pressed.
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