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Effects of Atmospheric Pressure Changes
A change in atmospheric 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 atmos-
pheric 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.
Summary of Contents for ST-4000 CHRONO
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