Description:
A simple procedure has been devised for determining the curvature of a wave front emitted from a point source as the wave front passes a vertical line in a horizontally stratified medium. The procedure consists of adding a correction for spherical spreading to an expression valid for any long ranges which is formally identical with Snell's Law. The wave-front curvature also may be related to travel times from the source to points on the vertical line. Numerical examples are given. (This work was supported by the Office of Naval Research.)