  A wind passing over a surface may cause an instability in the surface such as
the flapping seen when wind blows across a flag or waves when wind blows across
water. We show that when a radially outflowing wind blows across a dense thin
rotating disk, an initially flat disk is unstable to warping. When the wind is
subsonic, the growth rate is dependent on the lift generated by the wind and
the phase lag between the pressure perturbation and the vertical displacement
in the disk caused by drag. When the wind is supersonic, the grow rate is
primarily dependent on the form drag caused by the surface. While the radiative
warping instability proposed by Pringle is promising for generating warps near
luminous accreting objects, we expect the wind driven instability introduced
here would dominate in objects which generate energetic outflows.
