Travel Reference
In-Depth Information
dropped and you can't always get a good satellite signal under forest canopies, below high
cliffs or in snow or hail.
Altimeter
Altimeters determine altitude by measuring air pressure, which can fluctuate with temperat-
ure at any given elevation. Calibrate altimeters regularly at known elevations such as spot
heights and passes. Use the altimeter in conjunction with other navigation techniques to fix
your position. For instance, taking a back bearing to a known peak or river confluence, de-
termining the general direction of the track and obtaining your elevation should give you a
pretty good fix on your position.
Altimeters can also provide a general idea of barometric pressure trends and are useful for
indicating changing weather conditions. If the altimeter shows increasing elevation while
you are not climbing, it means the air pressure is dropping and a low-pressure weather sys-
tem may be approaching.
Watch the Weather
Expect the Unexpected
The Crowded House song 'Four Seasons in One Day' is a popular adage for NZ's unpredict-
able and occasionally extreme weather.
The usual weather pattern in NZ is a cycle of high-pressure systems (anticyclones or
ridges) followed by low-pressure systems (troughs or depressions), travelling west to east.
Anticyclones normally pass the northern portions of the country at intervals of three to sev-
en days, bringing fine weather with light or moderate winds. In between are depressions of
rain, strong winds and lower temperatures.
Because most of the country's mountain ranges run roughly north-south, they make their
own weather. It is not uncommon to have rain on the windward (western side) of a range,
fine weather on the lee side, and miserable conditions of heavy wind and rain along the
ridge tops.
