Altimeters need to be reset from known elevations fairly often because of high or low pressure weather systems.

When your camp site gets higher over night the weather is likely to turn bad. If you are below sea level it is likely the weather is good.

An altimeter is helpful for navigation in the mountains. No so much in Florida.
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"In theory, theory and practice are the same. In practice, they are not."
Yogi Berra