Gravity-Driven Winds (IMAGE) University of Pittsburgh Caption Contour visualization of the mixed-mode instabilities in the Prandtl model for a slope angle of 30 (deg). Flow is from top to bottom. Vortical structures are identified using the Q-criterion. Credit Inanc Senocak Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.