The ability to blow smoke rings is, perhaps, the mark of a man or woman with too much time on their hands. But think again – a smoke ring is a phenomenon known in the study of fluid dynamics as a toroidal vortex, which occurs naturally when volcanos puff smoke through round craters into the sky. But in the underwater realm, it turns out that blowing air bubbles in the shape of smoke rings is a popular past time enjoyed by dolphins, manatees, whales and, of course, humans. Take a look at this toroidal vortex footage (from 0:52 on the video) and prepare to be amazed.
Unhappily, the end sequence is also beautiful – the blast rings from an atomic explosion are also examples of a toroidal vortex, but the peaceful playfulness of the dolphins is what stays in the brain after watching the video.
Vortex rings were first mathematically analyzed by the German physicist Hermann von Helmholtz and are most commonly understood by boaters to mean the rings of bubbles created by the typical screw propeller beneath a boat engine.
Engine noise is certainly attractive to dolphins as they never miss the chance to swim alongside a boat buzzing through the water. Perhaps it's all to do with the toroidal vortex...
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