Radiation angle depends on surface wave speed via s equals c over cosθ

Evidence

The angle θ between the tangent to the surface and the leaving beams is related to the speed s of the surface waves as s = c/cosθ, where θ is the angle of incidence the wave makes with the surface. — Eric J. Heller, Why You Hear What You Hear- An…, 684

Categorization

• DEFINE: States the exact geometric relation between supersonic surface-wave speed and the angle at which sound is beamed off the surface.