Show that rays in a linear velocity gradient of the form v = a + bz will have ray paths that are circular. Derive an expression for the radius of the circle in terms of b and the ray parameter p. (It...

Show that rays in a linear velocity gradient of the form v = a + bz will have ray

paths that are circular. Derive an expression for the radius of the circle in terms of

b and the ray parameter p. (It is also possible to derive a more general constraint,

applying to ray geometries for linear velocity gradients in anisotropic media (see

Shearer and Chapman, 1988); the circular result for isotropic media follows as a

special case.)