Hydrostatic pressure and air pressure

The hydrostatic pressure is the pressure which is generated by the influence of the weight force within resting liquid substances. The hydrostatic pressure in a liquid substance increases with depth of immersion.

The air pressure is the hydrostatic pressure of the air. It is generated by the weight force of the air column which is located above a body respectively above the surface of the earth.

The hydrostatic pressure is calculated by:

p = ρ ⋅ g ⋅ h

It is:
p - hydrostatic pressure
ρ - density of the liquid substance respectively of the gas
g - acceleration of gravity (at our latitudes approx. 9,81 m/s²)
h - height of the liquid column above the measuring point

For example it is:
Density of water: 1 kg/dm³ bzw. 1 kg/Liter
Density of air: 1,2 g/dm³ bzw. 1,2 g/Liter

The pressure acts in all directions, so the forces act both downwards and upwards and of course laterally, too.