Mass path
= Mass path
{title2=$W_i=\int\rho_i\,dz$}
The column <mass> of a specified constituent per unit horizontal <area>, $W_i=\int\rho_i\,dz$. Under <hydrostatic equilibrium> it is $g^{-1}\int q_i\,dp$, where $q_i$ is the constituent mass fraction.