(1)	$\begin{array}{l}\displaystyle \frac{dp}{dz}= \rho(p) \cdot g\end{array}$

Approximations

Incompressible fluids

(2)	$\begin{array}{l}\displaystyle p(z) = p_0 + \rho \cdot g \cdot (z-z_0)\end{array}$

(3)	$\begin{array}{l}\displaystyle p(z) = p_0 \cdot \exp \left[ - \frac{M \, g}{R \, T} \cdot (z-z_0) \right]\end{array}$

Also known as Hydrostatic Boltzmann pressure distribution

Full-range model

(4)	$\begin{array}{l}\displaystyle \frac{1+ c_0 \, p(z)}{1 + c_0 \, p_0} = \exp \left[ \frac{ с_0 \cdot \rho_0 \cdot g \cdot (z-z_0)}{1+c_0 \, p_0} \right]\end{array}$

The pressure drop between two points is going to be:

(5)	$\begin{array}{l}\displaystyle p_2 - p_1 = \frac{ (1+c_0 \, p_1)}{c_0} \cdot \left( \exp \left[ \frac{ с_0 \cdot \rho_0 \cdot g \cdot (z_2-z_1)}{1+c_0 \, p_0} \right] - 1 \right)\end{array}$