Editing Vortex ring (section)

{{Short description|Torus-shaped vortex in a fluid}}
[[File:Vortex Ring Gun Schlierin.jpg|thumb|250px| Spark photography image of a vortex ring in flight.]]

A '''vortex ring''', also called a '''toroidal vortex''', is a [[torus]]-shaped [[vortex]] in a [[fluid]]; that is, a region where the fluid mostly spins around an imaginary axis line that forms a closed loop.  The dominant flow in a vortex ring is said to be [[toroid (geometry)|toroid]]al, more precisely [[poloidal]].{{clarify|reason=How can something be both toroidal and poloidal? They refer to two different directions on a torus.|date=March 2020}}

Vortex rings are plentiful in [[turbulence|turbulent]] flows of liquids and gases, but are rarely noticed unless the motion of the fluid is revealed by suspended particles—as in the [[smoke ring]]s which are often produced intentionally or accidentally by smokers.  Fiery vortex rings are also a commonly produced trick by [[fire eater]]s.  Visible vortex rings can also be formed by the firing of certain [[artillery]], in [[mushroom cloud]]s, in [[microburst]]s,<ref>{{Cite web |url=http://www-frd.fsl.noaa.gov/~caracena/micro/MBVoring.htm |website = Forecast Research Branch|publisher= NASA|title=The Microburst as a Vortex Ring |archive-url=https://web.archive.org/web/20110718120142/http://www-frd.fsl.noaa.gov/~caracena/micro/MBVoring.htm |archive-date=2011-07-18 |url-status=dead |access-date=2010-01-10}}</ref><ref>{{Cite book |url=https://history.nasa.gov/monograph29.pdf |title=Concept to Reality: Contributions of the Langley Research Center to US Civil Aircraft of the 1990s |last=Chambers |first=Joseph R. |date=Jan 1, 2003 |publisher=NASA |pages=185–198 |chapter=Wind Shear |hdl=2060/20030059513 |access-date=2007-10-09 |chapter-url=http://oea.larc.nasa.gov/PAIS/Concept2Reality/wind_shear.html |archive-url=https://web.archive.org/web/20071009144924/http://oea.larc.nasa.gov/PAIS/Concept2Reality/wind_shear.html |archive-date=2007-10-09 |url-status=dead}}</ref> and rarely in volcanic eruptions.<ref name=ABCNews>{{cite news |title=Vortex rings made of water vapour rise from Italy's Mount Etna volcano |url=https://www.abc.net.au/news/2024-04-08/mount-etna-volcanic-vortex-rings/103680958 |access-date=8 April 2024 |publisher =[[ABC News (Australia)|ABC News]] |date=8 April 2024}}</ref>

A vortex ring usually tends to move in a direction that is perpendicular to the plane of the ring and such that the inner edge of the ring moves faster forward than the outer edge.  Within a stationary body of fluid, a vortex ring can travel for relatively long distance, carrying the spinning fluid with it.