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Operation Guide 3258
E-48
Barometric Pressure
• Barometric pressure is displayed in units of 1 hPa (or 0.05 inHg).
•
The displayed barometric pressure value changes to
- - -
if a measured
barometric pressure falls outside the range of 260 hPa to 1,100 hPa (7.65
inHg to 32.45 inHg). The barometric pressure value will reappear as
soon as the measured barometric pressure is within the allowable range.
Temperature
• Temperature is displayed in units of 0.1°C (or 0.2°F).
• The displayed temperature value changes to
- - -
°C (or °F) if a
measured temperature falls outside the range of –10.0°C to 60.0°C
(14.0°F to 140.0°F). The temperature value will reappear as soon as
the measured temperature is within the allowable range.
Display Units
You can select either hectopascals (hPa) or inchesHg (inHg) as the display unit for the measured
barometric pressure, and Celsius (°C) or Fahrenheit (°F) as the display unit for the measured temperature
value. See “To specify temperature, barometric pressure, and altitude units” (page E-70).
Barometric Pressure Graph
Barometric pressure indicates changes in the atmosphere. By monitoring
these changes you can predict the weather with reasonable accuracy.
This watch takes barometric pressure measurements automatically every
two hours (at the 30th minute of every even numbered hour).
Measurement results are used to produce barometric pressure graph and
barometric pressure differential pointer readings.
Temperature
Barometric pressure
change indicator
Barometric
pressure
Temperature
Barometric pressure
change indicator
Barometric
pressure
Barometric pressure graphBarometric pressure graph
E-49
Reading the Barometric Pressure Graph
The barometric pressure graph shows readings of previous measurements for up to 10 hours.
• The horizontal axis of the graph represents time, with each dot standing for
two hours. The rightmost dot represents the most recent reading.
• The vertical axis of the graph represents barometric pressure, with each
dot standing for the relative difference between its reading and that of the
dots next to it. Each dot represents 1 hPa.
The following shows how to interpret the data that appears on the barometric pressure graph.
Rising barometric pressure indicates that upcoming weather will improve.
Falling barometric pressure indicates that upcoming weather will deteriorate.
Note
• If there are sudden changes in weather or temperature, the graph line of past
measurements may run off the top or bottom of the display. The entire graph will
become visible once barometric conditions stabilize.
• The following conditions cause the barometric pressure measurement to be skipped,
with the corresponding point on the barometric pressure graph being left blank.
– Barometric reading that is out of range (260 hPa to 1,100 hPa or 7.65 inHg to 32.45
inHg)
– Sensor malfunction
Barometric
pressure
Time
Barometric
pressure
Time
Not visible on
the display.
Not visible on
the display.
E-50
Barometric Pressure Differential Pointer
This pointer indicates the relative difference between the most recent
barometric pressure reading indicated on the barometric pressure graph
(page E-48), and the current barometric pressure value displayed in the
Barometer/Thermometer Mode (page E-47).
Reading Barometric Pressure Differential Pointer
Pressure differential is indicated in the range of
±10 hPa, in 1-hPa units.
• The nearby screen shot, for example, shows
what the pointer would indicate when the
calculated pressure differential is
approximately – 5 hPa (approximately –0.15
inHg).
• Barometric pressure is calculated and
displayed using hPa as the standard. The
barometric pressure differential also can be
read in inHg units as shown in the illustration
(1 hPa
=
0.03 inHg).
Barometric
pressure
differential
pointer
Barometric
pressure
differential
pointer
−0.15
−5
−10
−0.3
Barometric pressure
differential pointer
inHg values
hPa values
Current pressure
greater than most
recent measured
pressure
Current pressure
less than most
recent measured
pressure
−0.15
−5
−10
−0.3
Barometric pressure
differential pointer
inHg values
hPa values
Current pressure
greater than most
recent measured
pressure
Current pressure
less than most
recent measured
pressure
E-51
Barometric Pressure Change Indicator
The watch analyzes the last 10 hours of barometric pressure. If it determines that there has been a
signifi cant change in pressure, it displays a barometric pressure change indicator. For example, you can
start barometric pressure measurement when you arrive at a mountain lodge or campground for the night.
The following morning you can check for changes and plan your day accordingly.
Reading the Barometric Pressure Change Indicator
Indicator Meaning
Sudden rise in pressure.
Sudden fall in pressure.
Sustained fall in pressure, changing to a rise.
Sustained rise in pressure, changing to a fall.
• The barometric pressure change indicator is not displayed if there has been no noteworthy change in
barometric pressure.
E-52
Important!
• To ensure proper results, take barometric readings under conditions where the altitude remains
constant.
Example
– In a lodge or campground
– On the ocean
• A change in altitude causes a change in barometric pressure. Because of this, correct readings are
impossible. Do not take readings while ascending or descending a mountain, etc.
• The barometric pressure change indicator may appear at any time while the watch is in the Barometer/
Thermometer Mode. Keep in mind, however, that its indication will not be correct unless the watch has
been in an location where there was no change in altitude over the past several hours.
Pressure Sensor and Temperature Sensor Calibration
The pressure sensor and temperature sensor built into the watch are calibrated at the factory and normally
require no further adjustment. If you notice serious errors in the pressure readings and temperature
readings produced by the watch, you can calibrate the sensor to correct the errors.
Important!
• Incorrectly calibrating the barometric pressure sensor can result in incorrect readings. Before
performing the calibration procedure, compare the readings produced by the watch with those of
another reliable and accurate barometer.
• Incorrectly calibrating the temperature sensor can result in incorrect readings.
Carefully read the following before doing anything.
–
Compare the readings produced by the watch with those of another reliable and accurate thermometer.
– If adjustment is required, remove the watch from your wrist and wait for 20 or 30 minutes to give the
temperature of the watch time to stabilize.
E-53
To calibrate the pressure sensor and the temperature sensor
1. Take a reading with another measurement device to determine the
exact current barometric pressure or temperature.
2. With the watch in the Timekeeping Mode or in any of the sensor
modes, press
B
to enter the Barometer/Thermometer Mode.
3. Hold down
E
until
SET Hold
appears on the display and then the
current settings start to fl ash.
4. Press
D
to move the fl ashing between the temperature value and
barometric pressure value, to select the one you want to calibrate.
5. Use
A
(+) and
C
(
–
) to select the temperature and barometric
pressure value display units as shown below.
Temperature 0.1°C (0.2°F)
Barometric Pressure 1 hPa (0.05 inHg)
• To return the currently fl ashing value to its initial factory default
setting, press
A
and
C
at the same time. OFF will appear at
the fl ashing location for about one second, followed by the initial
default value.
6. Press
E
to return to the Barometer/Thermometer Mode screen.
E-54
Barometer and Thermometer Precautions
• The pressure sensor built into this watch measures changes in air pressure, which you can then apply
to your own weather predictions. It is not intended for use as a precision instrument in offi cial weather
prediction or reporting applications.
• Sudden temperature changes can affect pressure sensor readings.
• Temperature measurements are affected by your body temperature (while you are wearing the watch),
direct sunlight, and moisture. To achieve a more accurate temperature measurement, remove the
watch from your wrist, place it in a well ventilated location out of direct sunlight, and wipe all moisture
from the case. It takes approximately 20 to 30 minutes for the case of the watch to reach the actual
surrounding temperature.
E-55
Taking Altitude Readings
The watch displays altitude values based on air pressure readings taken by a built-in pressure sensor.
How the Altimeter Measures Altitude
The altimeter can measure altitude based on its own preset values (initial default method) or using a
reference altitude specifi ed by you.
When you measure altitude based on preset values
Data produced by the watch’s barometric pressure sensor is converted to approximate altitude based on
ISA (International Standard Atmosphere) conversion values stored in watch memory.
When you measure altitude using a reference altitude specifi ed by you
After you specify a reference altitude, the watch uses that value to convert
barometric pressure readings to altitude (page E-61).
• When mountain climbing, you can specify a reference altitude value in
accordance with a marker along the way or altitude information from a
map. After that, the altitude readings produced by the watch will be more
accurate than they would without a reference altitude value.
400
A
B
400
A
B