Fluid flows around a bend in a vortex. This design produces a continuous flow with equal volume and no vortex. The chemistry of the Antarctic polar vortex has created severe ozone depletion. This is applied by air jet or vortex tube. Saturn's south pole is the only known hot polar vortex in the solar system. Most insects use a method that creates a spiralling leading edge vortex. The strongest winds occurred in small subvortices along the south side of the main vortex. Ultrasonic measurements may be limited through barrier layers with large salinity, temperature or vortex differentials. A canard delta foreplane creates its own trailing vortex. As it rises, it displaces air which descends outside the core of the vortex. This produces a vortex within the vessel. These wings often use aerodynamic devices like flaps, slots, slats, and vortex generators. It can be analysed in terms of the vortex produced by rotation. The setbacks and rounded edges of the building combat vortex formation. This relates to Descartes' vortex theory.