The vortex that forms in “Dust Devil” is similar to tornadoes and dust devils, familiar phenomena on Earth and on other planets.  A fundamental law of nature explains the formation of a dust devil.  When either water or air moves quickly over a surface, it exerts less pressure on the surface than when it moves more slowly.  This behavior, which is described by the Bernoulli Principle, is the underlying cause of vortices.  Wind that encounters an obstacle must flow more quickly around the obstacle than nearby wind, which can continue on a straighter course.  The wind that curves around the obstacle is easily deflected into a spin with a low-pressure zone at its center.  This air spinning around a low-pressure zone is a vortex.

The formation of a vortex around an obstacle is perhaps understandable through an analogy with ice skaters.  If a moving skater clasps hands with a standing skater, who then pulls her toward him (like the object deflecting the path of the moving fluid) the moving skater arcs into a deflected path and her body is set into a spin around the standing skater.  When they release hands, the moving skater flies off in a straight line along the new, deflected, path, and the spin started by her brief connection with the stationary skater continues.

A vortex remains constant unless acted upon by an external force, as described by the law of conservation of angular momentum. According to this law, the movement of spinning matter — which is the product of the spinning matter’s mass, rate of spin, and distance from the center of its spin — remains constant unless changed by an external force.  Therefore, as spinning matter moves toward the center of its spin, assuming its mass remains constant, the rate of spinning accelerates.  We see this phenomenon when a spinning skater accelerates her spin by drawing her arms in toward her body.  

Once the spin is in motion, the lower pressure inside the vortex helps hold it together.  The low-pressure zone can also draw dust up into the vortex, making it visible.  A vortex may seem to appear and disappear as the quantity of visible particles caught up in it changes from moment to moment.

A vortex will spin forever unless forces act to stop it.  This explains the continuous orbiting of the planets.  The Solar System is a huge vortex, one that has been spinning around the Sun for more than five billion years in the frictionless environment of outer space.

Dust devils and tornadoes spin in the atmosphere, or near the surface, of the Earth and other planets.  Friction imposed by this environment will finally rob a vortex of its energy, and the vortex will dissipate.

It is possible for a vortex to be blown around without dissipating for a long while.  Therefore you may see a tornado or a dust devil, which is a form of tornado, in a location far from where it was created.

A vortex forms on a small scale, as in a dust devil, when wind encounters an obstacle, like a boulder or a cliff or a hill.  On an even smaller scale, vortices are observable in water draining out of the sink or bathtub, or when a pile of fallen leaves rises in a small whirlwind.