Seeing is Believing

Marine acoustician Tim Duda uses a novelty wave tank to demonstrate what it is difficult to see in the ocean: how differences in fluid properties can lead to waves beneath the waves. Duda studies a phenomenon called internal waves, which form along the intersection of waters of different density or temperature in the interior of the ocean (such as saltier water flowing beneath fresher water). These waves can pulse through a sea in cyclic frequencies known as internal tides. (Photo by Tom Kleindinst, Woods Hole Oceanographic Institution)