Operation Guide 3258
Barometric pressure change indicator
BarometricTemperature pressure
Display Units
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
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
Barometric |
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pressure |
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| • The vertical axis of the graph represents barometric pressure, with each |
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| dot standing for the relative difference between its reading and that of the |
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| dots next to it. Each dot represents 1 hPa. |
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| Time | ||||
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.
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
Barometric Pressure Graph
Barometric pressure graph | Barometric pressure indicates changes in the atmosphere. By monitoring | |
these changes you can predict the weather with reasonable accuracy. | ||
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| 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. | |
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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. | Not visible on |
– Barometric reading that is out of range (260 hPa to 1,100 hPa or 7.65 inHg to 32.45 | the display. |
inHg) |
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– Sensor malfunction |
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Barometric Pressure Differential Pointer
| This pointer indicates the relative difference between the most recent |
Barometric | barometric pressure reading indicated on the barometric pressure graph |
pressure | (page |
differential | Barometer/Thermometer Mode (page |
pointer |
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Barometric Pressure Change Indicator
The watch analyzes the last 10 hours of barometric pressure. If it determines that there has been a significant 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 Barometric Pressure Differential Pointer
Pressure differential is indicated in the range of | inHg values | |
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±10 hPa, in | hPa values | |
• The nearby screen shot, for example, shows | ||
what the pointer would indicate when the |
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calculated pressure differential is |
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approximately – 5 hPa (approximately – 0.15 |
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inHg). |
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• Barometric pressure is calculated and |
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displayed using hPa as the standard. The |
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barometric pressure differential also can be |
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read in inHg units as shown in the illustration |
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(1 hPa = 0.03 inHg). |
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| Barometric pressure | |
| differential pointer | |
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Current pressure greater than most
recent measured pressure
−5
−0.15
−10
Current pressure
−0.3less than most recent measured
pressure
Reading the Barometric Pressure Change Indicator
Indicator | Meaning |
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| Sudden rise in pressure. |
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| Sudden fall in pressure. |
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| Sustained fall in pressure, changing to a rise. |
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| Sustained rise in pressure, changing to a fall. |
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•The barometric pressure change indicator is not displayed if there has been no noteworthy change in barometric pressure.
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.
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 flash.
4. Press D to move the flashing between the temperature value and barometric pressure value, to select the one you want to calibrate.
5. Use A (+) and C
Temperature | 0.1°C (0.2°F) |
Barometric Pressure | 1 hPa (0.05 inHg) |
•To return the currently flashing value to its initial factory default
setting, press A and C at the same time. OFF will appear at the flashing location for about one second, followed by the initial default value.
6. Press E to return to the Barometer/Thermometer Mode screen.
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 official 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.
Taking Altitude Readings
The watch displays altitude values based on air pressure readings taken by a
How the Altimeter Measures Altitude
The altimeter can measure altitude based on its own preset values (initial default method) or using a reference altitude specified 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 specified by you
After you specify a reference altitude, the watch uses that value to convert |
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barometric pressure readings to altitude (page | B |
• When mountain climbing, you can specify a reference altitude value in | |
accordance with a marker along the way or altitude information from a | A |
map. After that, the altitude readings produced by the watch will be more | |
accurate than they would without a reference altitude value. | 400 |
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