[pct-l] how an altimeter works, take 2

[Lenny Leum]

The question remains though, how does the watch supposedly determine which pressure change is due to elevation
and which pressure change is due to changes in weather?  I can see that this contradiction is what makes it inaccurate, but, does the device generally assume a steady barometer?  I'm just wondering if these devices are "smart" and how that works.
Lenny