7.
Backlight
To activate the backlight, press and hold the
ALTI
button for three seconds. The backlight will remain
on for 30 seconds of inactivity.
8.
Low Battery Indicator
When the low battery indicator icon is displayed
, it is time to replace the battery.
9.
Discussion of Features and Limitations
9.1
Weather Forecasting
The weather forecast or pressure tendency is based on the rate of change of barometric pressure. In
general, when the pressure increases, the weather improves (sunny to partly cloudy) and when the
pressure decreases, the weather degrades (cloudy to rain).
The weather forecast is an estimation or generalization of weather changes in the next 24 to 48 hours,
and varies from location to location. It is not an indication of current conditions. The tendency is
simply a tool for projecting weather conditions and is never to be relied upon as an accurate method to
predict the weather.
Barometric pressure is adversely affected by altitude and to a lesser extent, changes in weather
conditions. The weather forecasting tool is only useful at a fixed position and must be reset to the
current weather conditions if you change altitude. Thus, if you are hiking, climbing or driving, and
continuously changing altitude, the weather forecasting tool must be recalibrated.
9.2
Magnetic Declination
Magnetic declination is defined as the angle between magnetic north (the direction the north end of a
compass needle points) and true north. Only a GPS can determine true north by knowing your exact
orientation on the earth. All digital compasses measure magnetic north.
The declination is positive when the magnetic north is east of true north. The declination is negative
when the magnetic north is west of true north. To determine the declination for your location, visit:
http://www.ngdc.noaa.gov/geomagmodels/Declination.jsp
For example, Phoenix, AZ produces the following result:
Declination = 10° 59' E changing by 0° 6' W/year (or +10 degrees 59 minutes changing –6 minutes
per year).
To convert to decimal format:
Declination = 10° + 59’/60 (‘/°) = 10.98° (rounded to the nearest integer, Declination = 11°).
Enter
+11
into the display. This will offset magnetic north by +11 degrees (or 11 degrees to the East)
to true north.
Note that the magnetic declination changes as a function of time for your location. In the above
example, the declination changes -6 minutes (or 0.10° per year, or about 1° every 10 years). Thus, the
time function is insignificant.
Version
1.1
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2011,
Ambient
LLC.
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Reserved.
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