pressure was read by height of mercury in the glass tube. We have a bug to fake the shadow for the BottomAppBar, but it's not as trivial as BottomNavigation for instance because the fab can move and change shape, so the shadow should change as well. This means shadows are generally not visible on top of Views. You've seen the films ' The glass is falling fast Captain a storms a coming!'. There is a light source from the top and a light source directly in the middle. Incidentally the pressure change could help you predict the weather. Set it to the known height or pressure and walk up or down a slope and it will display the mapped heights very closely, don't forget you are probably reading it above waist height so allow for that, this reading will give you a location on a good contoured map of your point on the trail up or down the slope but if you then camped for the night air pressure will have changed and so your altitude reading will be incorrect and require resetting, which you can do with that map if you can pinpoint yourself on a contour line. If the altitude is derived from the barometer which some gpses have ( my experience is of Garmins) and some smart watches have it can be very accurate for a short time but it will drift as the weather changes. In my experience of walking with various GPSes and smart phones over the last 14 years the altitude derived by the satellites won't be good, no where near as good as the 3 to 5 meters or so of the horizontal accuracy you can normally rely on.

Cannot get elevation expert gps