Head wave movie
A charge is detonated in the upper left hand corner generating a pair of expanding rings. The red and blue rings show regions of high and low pressure respectively.
The expanding rings hit the ocean bottom. At the point of contact, the energy is split between a reflected wave in the ocean and a transmitted wave in the ocean bottom. The reflected wave is distorted since the phase of the reflection coefficient varies between 0 and 90 degrees depending on the angle of incidence. The transmitted wave preserves its shape but stretches because the sound speed in the bottom is faster.
The wave in the ocean bottom travels faster and pulls ahead of the water wave. Energy is continuously shed from the ocean bottom and forms a diagonal band (the head wave=lateral wave=conical wave) connecting the transmitted and reflected waves.
Start (requires an mpeg movie player)