Pressure exerted by a liquid due to its height is called column pressure.
Consider two points X and Y to be lying on the top and bottom circular faces of an imaginary cylinder of liquid. Let area of the circular faces by a each and height of the cylinder by h. If pressure exerted at point X is Px and at Y is Py, then
\(P_x=\frac{F_x}{a}\)
Fx = Pxa acting downward Weight of this cylinder, W = mg = Vρg = ahρg is also acting downwards so total downward force = Fx + W = Pxa + ahρg
The lower face of the cylinder experiences upward force given by
Fy = Pya.
In equilibrium, Fy = Fx + W
i.e., Pya = Pxa + ahρg
or (Px − Py) = hρg
or P = hρg
