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, although the word cyclone is used in meteorology to name a weather system with a low-pressure area in the center around which, from an observer looking down toward the surface of the Earth, winds blow counterclockwise in the Northern Hemisphere and clockwise in the Southern. Tornadoes come in many shapes and sizes, and they are often visible in the form of a condensation funnel originating from the base of a cumulonimbus cloud, with a cloud of rotating debris and dust beneath it. Most tornadoes have wind speeds less than 180 kilometers per hour, are about 80 meters across, and travel several kilometers before dissipating. The most extreme tornadoes can attain wind speeds of more than 480 kilometers per hour (300 mph), are more than 3 kilometers (2 mi) in diameter, and stay on the ground for more than 100 km.
These are some notable tornadoes, tornado outbreaks, and tornado outbreak sequences that have occurred around the globe.
- Exact death and injury counts are not possible; especially for large events and events before 1955.
- Prior to 1950 in the United States, only significant tornadoes are listed for the number of tornadoes in outbreaks.
- Due to increasing detection, particularly in the U.S., numbers of counted tornadoes have increased markedly in recent decades although the number of actual tornadoes and counted significant tornadoes has not. In older events, the number of tornadoes officially counted is likely underestimated.
Tornado Alley is a loosely defined area of the central United States and Canada where tornadoes are most frequent. The term was first used in 1952 as the title of a research project to study severe weather in areas of Texas, Louisiana, Oklahoma, Kansas, South Dakota, Iowa and Nebraska. Tornado climatologists distinguish peaks in activity in certain areas and storm chasers have long recognized the Great Plains tornado belt.
Oceanic and Atmospheric Research (OAR) is a division of the National Oceanic and Atmospheric Administration (NOAA). OAR is also referred to as NOAA Research.
The National Severe Storms Laboratory (NSSL) is a National Oceanic and Atmospheric Administration (NOAA) weather research laboratory under the Office of Oceanic and Atmospheric Research. It is one of seven NOAA Research Laboratories (RLs).
The Enhanced Fujita 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 TOtable Tornado Observatory is a large, instrumented barrel-shaped device invented in 1979 by engineers Dr. Al Bedard and Carl Ramzy of the National Oceanic and Atmospheric Administration (NOAA) Environmental Technology Laboratory (ETL), and Dr. Howard Bluestein, meteorologist at the University of Oklahoma (OU). NOAA's objective was to place the TOTO directly in the path of a tornado, where it could, theoretically, record valuable information about the tornado's structure. The device's nickname, TOTO, originates from Toto the dog in Metro-Goldwyn-Mayer's 1939 film The Wizard of Oz, in which a tornado is a key plot element.
Neil Burgher Ward was an American meteorologist who is credited as the first scientific storm chaser, developing ideas of thunderstorm and tornado structure and evolution as well as techniques for forecasting and severe weather intercept. He also was a pioneering developer of physical models of tornadoes, first at his home, then at the National Severe Storms Laboratory (NSSL) in Norman, Oklahoma. He significantly furthered the modern scientific understanding of atmospheric vortices, particularly tornadoes.
Harold Edward Brooks is an American meteorologist whose research is concentrated on severe convective storms and tornadoes, particularly severe weather climatology, as well as weather forecasting.
The Verification of the Origins of Rotation in Tornadoes Experiment are field experiments that study tornadoes. VORTEX1 was the first time scientists completely researched the entire evolution of a tornado with an array of instrumentation, enabling a greater understanding of the processes involved with tornadogenesis. A violent tornado near Union City, Oklahoma was documented in its entirety by chasers of the Tornado Intercept Project (TIP) in 1973. Their visual observations led to advancement in understanding of tornado structure and life cycles.
The European Severe Storms Laboratory (ESSL) is a scientific organisation that conducts research on severe convective storms, tornadoes, intense precipitation events, and avalanches across Europe and the Mediterranean. It operates the widely consulted European Severe Weather Database (ESWD).
Erik Nels Rasmussen is an American meteorologist and leading expert on mesoscale meteorology, severe convective storms, forecasting of storms, and tornadogenesis. He was the field coordinator of the first of the VORTEX projects in 1994-1995 and a lead principal investigator for VORTEX2 from 2009-2010 and VORTEX-SE from 2016-2017, as well as involved in other smaller VORTEX offshoots and many field projects.
The following is a glossary of tornado terms. It includes scientific as well as selected informal terminology.
Louis John Wicker is an American atmospheric scientist with expertise in numerical analysis, numerical simulation, and forecasts of severe convection and tornadoes. Doing storm chasing field research, Wicker deployed the TOtable Tornado Observatory (TOTO) and was in leadership roles in the VORTEX projects. He is also known for pioneering work simulating convection at the National Center for Supercomputing Applications (NCSA) at the University of Illinois at Urbana–Champaign (UIUC).
Adam James Clark is an American meteorologist at the Cooperative Institute for Mesoscale Meteorological Studies (CIMMS) and the National Severe Storms Laboratory (NSSL) recognized for contributions to numerical modeling of convection.
David Jonathan Stensrud is an American meteorologist recognized for numerical modeling and forecasting of hazardous synoptic and mesoscale weather and for incorporating new data into models.
David Owen Blanchard is an American meteorologist, photographer, and storm chaser. He was a significant collaborator in seminal research on tornadogenesis, specifically the importance of baroclinic boundaries, the rear-flank downdraft (RFD) and its thermodynamic characteristics.
Donald W. Burgess is an American meteorologist who has made important contributions to understanding of severe convective storms, particularly tornadoes, radar observations and techniques, as well as to training other meteorologists. He was a radar operator during the first organized storm chasing expeditions by the University of Oklahoma (OU) in the early 1970s and participated in both the VORTEX projects.
Edwin Kessler III was an American atmospheric scientist who oversaw the development of Doppler weather radar and was the first director of the National Severe Storms Laboratory (NSSL).
James F. "Jeff" Kimpel was an American atmospheric scientist with expertise on severe storms who was a provost of the University of Oklahoma (OU) and director of the National Severe Storms Laboratory (NSSL).
