deep isothermal layer

8.36  deep isothermal layer. Ocean layer below the thermocline extending to the bottom of the sea which has a nearly constant temperature and in which the velocity of sound increases with...

thermocline

8.35  thermocline. Ocean layer near the surface within which the water temperature decreases rapidly with increasing depth.

crossover range

8.34  crossover range. Range within which the propagation loss caused by divergence is equal to that caused by...

shadow zone

8.33  shadow zone. Zone of the ocean into which sound rays are unable to penetrate by reason of refraction or a physical barrier such as a seamount. Annotation              Although sound rays...

convergence zone

8.32  convergence zone. Region of the sea close to the surface where sound rays are concentrated at great range from the source by upward refraction over great depths.