Mass mixing ratio
= Mass mixing ratio
{title2=$q=\rho_a/\rho$}
The mass mixing ratio used in a dilute <radiative transfer> model is absorber <mass density> divided by total atmospheric <mass density>. A hydrostatic pressure interval contributes absorber <mass path> $q\,dp/g$. Some meteorological conventions divide by dry-air mass instead; the convention must be stated. A volume or mole mixing ratio instead contributes absorber moles $x\,dp/(gM)$, with background <molar mass> $M$.