Dynamics of transverse cloud rolls in the boundary layer with the Poiseuille shear flow

Abstract

This study examines the formation of transverse cloud rolls associated with the Poiseuille shear flows that are occasionally observed in the Earth's atmospheric boundary layer. It is shown that the mechanisms underlying the formation of this type of transverse roll clouds can be explained in the framework of the transition dynamics and structural bifurcation for the incompressible flows. Specifically, the formation of transverse roll clouds is attributed to a subtle interaction between the vertical wind shear and the vertical temperature gradient in the atmospheric well-mixed boundary layer, which results in an attractor bifurcation and subsequent boundary layer separations. The topological structure of the Poiseuille shear flow at the boundary layer separation can be identified as transverse roll cloud.