Types of waves
Although density is not the first
thing that comes to mind when we
think of the sea, waves are a different
matter. Waves are ubiquitous in
the ocean, in lakes, and of course on
beaches – and they are feared in their
destructive form as tsunamis.
Most of these waves are what physicists
call surface waves. But there are
also internal waves, which occur at
the interface between density layers of
water. In the ocean, breaking internal
waves mix up the water layers and lift
the nutrients they contain.