  In this study, the stability dependence of turbulent Prandtl number ($Pr_t$)
is quantified via a simple analytical approach. Based on the conventional
budget equations, a hybrid length scale formulation is first proposed and its
functional relationships to well-known length scales are established. Next, the
ratios of these length scales are utilized to derive an explicit relationship
between $Pr_t$ and gradient Richardson number. The results predicted by the
proposed formulation are compared against other competing formulations as well
as published datasets.
