Vortex
![Vortex created by the passage of an aircraft wing, revealed by colored smoke.](/Images/godic/202501/21/Airplane_vortex_edit1613.jpg")
![Vortices evidenced by milk in a cup of coffee](/Images/godic/202501/21/Milk_vortices1613.jpg")
![The Crow Instability of a jet aeroplane's contrail visually demonstrates the vortex created in the atmosphere (gas fluid medium) by the passage of the aircraft.](/Images/godic/202501/21/Crow_instability_contrail1613.JPG")
![A rigid-body vortex](/Images/godic/202501/21/Rotational_vortex1613.gif")
In fluid dynamics, a vortex is a region in a fluid in which the flow is rotating around an axis line, which may be straight or curved. The plural of vortex is either vortices or vortexes. Vortices form in stirred fluids, and may be observed in phenomena such as smoke rings, whirlpools in the wake of boat, or the winds surrounding a tornado or dust devil.