A wind turbine blade had a suction side surface and a pressure side surface. A plurality of vortex elements are formed on at least one of the suction side or the pressure side surfaces. The vortex elements have an upwardly inclined wind face and a downwardly inclined slip face, with the wind face and slip face meeting at a generally open-ended U-shaped ridge that defines side horns. The side horns decrease in height from a forward most portion of the ridge to the suction side surface or pressure side surface.