Definition from Wiktionary, the free dictionary
- A smoking trick where one blows or exhales rings of smoke.
2013 March 1, Frank Fish, George Lauder, “Not Just Going with the Flow”, in American Scientist, volume 101, number 2, page 114:
- An extreme version of vorticity is a vortex. The vortex is a spinning, cyclonic mass of fluid, which can be observed in the rotation of water going down a drain, as well as in smoke rings, tornados and hurricanes.
- A smoke ring persists for a surprisingly long time, illustrating the slow rate at which viscosity dissipates the energy of a vortex.