Multiple-vortex tornado
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A multiple-vortex tornado is a
tornado A tornado is a violently rotating column of air that is in contact with both the surface of the Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. It is often referred to as a twister, whirlwind or cyclone, altho ...
that contains several vortices (called subvortices or suction vortices) revolving around, ''inside'' of, and as part of the main
vortex In fluid dynamics, a vortex ( : vortices or vortexes) is a region in a fluid in which the flow revolves around an axis line, which may be straight or curved. Vortices form in stirred fluids, and may be observed in smoke rings, whirlpools in th ...
. The only times multiple vortices may be visible are when the tornado is first forming or when condensation and debris are balanced such that subvortices are apparent without being obscured. They can add over 100 mph to the ground-relative wind in a tornado circulation and are responsible for most cases where narrow arcs of extreme destruction lie right next to weak damage within tornado paths.


General

Suction vortices (or suction spots) are really substructures of many, perhaps all, tornadoes but are not always easily visible. These usually occur at the base of the tornado vortex where the tornado makes contact with the surface. Subvortices tend to form after vortex breakdown reaches the surface and are resultant from the ratio of cyclonically incoming and rising air motions. Multivortex structure is not unique to tornadoes, occurring in other circulations such as
dust devil A dust devil is a strong, well-formed, and relatively short-lived whirlwind. Its size ranges from small (half a metre wide and a few metres tall) to large (more than 10 m wide and more than 1 km tall). The primary vertical motion is u ...
s, but is a natural result of the physics of vortex dynamics. Multivortex tornadoes should not be confused with cyclically tornadic
supercell A supercell is a thunderstorm characterized by the presence of a mesocyclone: a deep, persistently rotating updraft. Due to this, these storms are sometimes referred to as rotating thunderstorms. Of the four classifications of thunderstorms (s ...
s. These systems can have the tendency to produce many, and very separate tornadoes, called tornado families, existing either at the same time or in succession. A phenomenon similar in nature to multiple vortices is the
satellite tornado A satellite tornado is a tornado that revolves around a larger, primary tornado and interacts with the same mesocyclone. Satellite tornadoes occur apart from the primary tornado and are not considered subvortices; the primary tornado and satellit ...
. It is different from a multiple-vortex tornado in that it exists ''outside'' of the main tornado and forms via a different mechanism.


Notable tornadoes

The destructive May 2011 EF5 Joplin, Missouri tornado was an example of a multiple-vortex tornado. The largest tornado ever documented was a multiple-vortex tornado. It struck El Reno, Oklahoma, on May 31, 2013, taking the lives of tornado researcher
Tim Samaras Timothy Michael Samaras (November 12, 1957 – May 31, 2013) was an American engineer and Storm chasing, storm chaser best known for his field research on tornadoes and time on the Discovery Channel show, ''Storm Chasers (TV series), Storm C ...
, his son Paul, and their
TWISTEX TWISTEX (a backronym for Tactical Weather-Instrumented Sampling in/near Tornadoes Experiment) was a tornado research experiment that was founded and led by Tim Samaras of Bennett, Colorado, US, that ended in the deaths of three researchers in ...
colleague, Carl Young. This storm also took the life of local amateur chaser Richard Henderson. It had a maximum width of and a maximum recorded windspeed of at least , however, because of a lack of intense property damage, the tornado achieved a rating of EF3 on the
Enhanced Fujita scale The Enhanced Fujita scale (abbreviated as EF-Scale) rates tornado intensity based on the severity of the damage they cause. It is used in some countries, including the United States, Canada, China, and Mongolia. The Enhanced Fujita scale repla ...
. Nevertheless, the El Reno tornado is one of the two strongest tornadoes ever recorded in terms of maximum wind speeds, the other being the
1999 Bridge Creek–Moore tornado On the evening of Monday, May 3, 1999, a large and exceptionally powerful F5 tornado registered the highest wind speeds ever measured globally; winds were recorded at by a Doppler on Wheels (DOW) radar. Considered the strongest tornado eve ...
which doppler radar measured mph, later revised to 301±20 mph.


See also

*
Tornadogenesis Tornadogenesis is the process by which a tornado forms. There are many types of tornadoes and these vary in methods of formation. Despite ongoing scientific study and high-profile research projects such as VORTEX, tornadogenesis is a volatile pro ...


References


External links


Multiple Vortex Tornado
at the Online Tornado FAQ {{Cyclones Tornado