I got this from
Suunto's FAQ section:
http://suunto.custhelp.com/cgi-bin/s...er/std_alp.php http://suunto.custhelp.com/cgi-bin/s...i=&p_topview=1
Question
The altimeter in my
Suunto wristop computer keeps going off height. I have several places where I know the actual height, but when I return to the same place the next day, the altitude has changed according to my
Suunto.
Answer
The altimeter in your
Suunto wristop computer calculates the altitude by measuring changes in the air pressure. This means that the instrument interprets changes in air pressure as changes in altitude, although air pressure changes may also be caused by changes in the weather. This is why it is always advisable to reset the reference altitude or the sea level pressure before undertaking a new activity.
As a basic rule, the altimeter will give you correct readings if the weather has not changed. The air weight is also affected by the outside temperature. As a result, the air pressure difference between altitudes is also dependent upon the air temperature. The altitude calculation of the wristop is based on the air pressure at certain normal temperatures. Each altitude has a definitive normal temperature. You should be able to find these normal temperatures in your manual under "Effects of Air Temperature on Altitude Measurement".
The real outside temperature does not always equal the normal temperature and this may cause altitude measurement errors. You can find the formula for calculating these errors in the manual as well. These reasons should explain why small errors in the altitude measurement may occur. Always remember to reset the reference altitude before recording with the wristop computer.