Describe the phenomenon or experience in which the effects of atmospheric pressure are manifested.

To clearly demonstrate the basic property of Atmospheric Pressure, we need; two points in space, which are different in height, above sea level and two corrected, identical barometers (a device for measuring atmospheric pressure).
To demonstrate the dependence of atmospheric pressure in relation to altitude, we need to take two readings from different points and compare them.
Seeing that with increasing altitude – the barometric pressure readings decrease.
This experience clearly shows the directly proportional dependence of the data of these two parameters: altitude (h) and atmospheric pressure (p).