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The Fujita scale (F-Scale), or Fujita-Pearson scale, is a scale for rating tornado intensity, based on the damage tornadoes inflict on human-built structures and vegetation. A tornado is a violent rotating column of air which is in contact with both the surface of the earth and a Cumulonimbus cloud or in rare cases the base of a Cumulus The official Fujita scale category is determined by meteorologists (and engineers) after a ground and/or aerial damage survey; and depending on the circumstances, ground-swirl patterns (cycloidal marks), radar tracking, eyewitness testimonies, media reports and damage imagery, as well as photogrammetry/videogrammetry if motion picture recording is available. Meteorology (from Greek grc μετέωρος metéōros, "high in the sky" and grc -λογία -logia) is the Interdisciplinary A civil engineer is a person who practices Civil engineering, one of the many engineering professions A cycloid is the curve defined by the path of a point on the edge of circular wheel as the wheel rolls along a straight line Radar is a system that uses electromagnetic waves to identify the range altitude direction or speed of both moving and fixed objects such as Aircraft, ships A witness is someone who has firsthand knowledge about a Crime or dramatic event through their Senses (e Photogrammetry is the first Remote sensing technology ever developed in which geometric properties about objects are determined from photographic images Videogrammetry is a measurement technology in which the three-dimensional coordinates of points on an object are determined by measurements made in two or more Video images taken
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Background
The scale was introduced in 1971 by Tetsuya "Ted" Fujita of the University of Chicago who developed the scale together with Allen Pearson (path length and width additions in 1973), head of the National Severe Storms Forecast Center (predecessor to the Storm Prediction Center) in Kansas City, Missouri. Year 1971 ( MCMLXXI) was a Common year starting on Friday (link will display full calendar of the 1971 Gregorian calendar. was a severe storms researcher of the twentieth century Born in Kitakyushu, Fukuoka Prefecture, Japan, he studied at Kyushu Institute of Technology The University of Chicago is a Private university located principally in the Hyde Park neighborhood of Chicago. Allen Pearson was the Director of the National Severe Storms Forecast Center from 1965-79 and began to collaborate with Dr Year 1973 ( MCMLXXIII) was a Common year starting on Monday (link will display full calendar of the 1973 Gregorian calendar. The Storm Prediction Center (SPC located in Norman, Oklahoma, is part of the National Centers for Environmental Prediction (NCEP operating under The Storm Prediction Center (SPC located in Norman, Oklahoma, is part of the National Centers for Environmental Prediction (NCEP operating under Kansas City Missouri only Items for the metro area Kansas City Kansas or North Kansas City MO should go on their respective pages The scale was applied retroactively to tornado reports from 1950 onward for the National Oceanic and Atmospheric Administration National Tornado Database in the United States, and occasionally to earlier infamous tornadoes. Year 1950 ( MCML) was a Common year starting on Sunday (link will display the full calendar of the Gregorian calendar. The National Oceanic and Atmospheric Administration ( NOAA) is a scientific agency within the United States Department of Commerce focused on the conditions of the Tom Grazulis of The Tornado Project also rated all known significant tornadoes (F2-F5 or causing a fatality) in the U. Thomas P Grazulis (b 1942 in Massachusetts is a Meteorologist who has written extensively about Tornadoes and is head of the Tornado Project. S. back to 1880. Year 1880 ( MDCCCLXXX) was a Leap year starting on Thursday (link will display the full calendar of the Gregorian calendar (or a Leap year Previously used in most areas outside of Great Britain, it was superseded in 2007 by the Enhanced Fujita Scale in the United States. See also Kingdom of Great Britain Great Britain (Breatainn Mhòr Prydain Fawr Breten Veur Graet Breetain is the larger of the two main islands Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. The Enhanced Fujita Scale, or EF Scale, is the scale for rating the strength of Tornadoes in the United States estimated via the damage they cause
Though each damage level is associated with a wind speed, the Fujita scale is a damage scale, and the wind speeds associated with the damage listed are unverified. The Enhanced Fujita Scale was formulated due to research which suggested that wind speeds for strong tornadoes on the Fujita scale are greatly overestimated. However, being determined by expert elicitation with top engineers and meteorologists, the EF scale wind speeds remain as educated guesses, and are also biased to United States construction practices. In Science, Engineering, and Research, expert elicitation is the synthesis of opinions of Experts of a subject where there is uncertainty due
Derivation
The original scale as derived by Fujita was a 13-level scale (F0-F12) designed to smoothly connect the Beaufort scale and the Mach number scale. The Beaufort scale (ˈboʊfət is an Empirical measure for describing Wind speed based mainly on observed sea conditions Mach number (\mathrm{Ma} or M (generally ˈmɑːk sometimes /ˈmɑːx/ or /ˈmæk/ is the speed of an object moving through air or any Fluid The gap between F0 and F1 corresponds to the eighth and twelfth levels of the Beaufort scale, "violent storm" and "hurricane" respectively. The Beaufort scale (ˈboʊfət is an Empirical measure for describing Wind speed based mainly on observed sea conditions On the original scale, the wind speeds for F11 and F12 corresponded to Mach numbers 0. Mach number (\mathrm{Ma} or M (generally ˈmɑːk sometimes /ˈmɑːx/ or /ˈmæk/ is the speed of an object moving through air or any Fluid 9 and 1. 0 respectively. This provided a smooth relationship between the three scales. From these wind speed numbers, qualitative descriptions of damage were made for each category of the Fujita scale, and then these descriptions were used to classify tornadoes. In the vernacular quality can mean a high degree of excellence (“a quality product” a degree of excellence or the lack of it (“work of average quality” or a property of [1] The diagram on the right illustrates the relationship between the Beaufort, Fujita, and Mach number scales.
At the time Fujita derived the scale, little information was available on damage caused by wind, so the original scale presented little more than educated guesses at wind speed ranges for specific tiers of damage. Wind speed is the Speed of Wind, the movement of air or other gases in an atmosphere Fujita intended that only F0-F5 be used in practice, as this covered all possible levels of damage to frame homes as well as the expected estimated bounds of wind speeds. He did, however, add a description for F6, which he phrased as "inconceivable tornado", to allow for wind speeds exceeding F5 and for possible future advancements in damage analysis which might show it. [2]
Furthermore, the original wind speed numbers have since been found to be higher than the actual wind speeds required to incur the damage described at each category. The error manifests itself to an increasing degree as the category increases, especially in the range of F3 through F5. The National Oceanic and Atmospheric Administration notes that …precise wind speed numbers are actually guesses and have never been scientifically verified. The National Oceanic and Atmospheric Administration ( NOAA) is a scientific agency within the United States Department of Commerce focused on the conditions of the Different wind speeds may cause similar-looking damage from place to place—even from building to building. Without a thorough engineering analysis of tornado damage in any event, the actual wind speeds needed to cause that damage are unknown. [2] Since then, the Enhanced Fujita Scale has been created using better wind estimates by engineers and meteorologists. The Enhanced Fujita Scale, or EF Scale, is the scale for rating the strength of Tornadoes in the United States estimated via the damage they cause
Parameters
The six categories are listed here, in order of increasing intensity. Note:
- When the relative frequency of tornadoes is mentioned, it is the relative frequency in the United States. The United States of America —commonly referred to as the Frequencies of strong tornadoes (F2 or greater) are significantly less elsewhere in the world. Parts of southern Canada, Bangladesh and adjacent areas of eastern India, and possibly a few other areas do have frequent severe tornadoes, however data is scarce and statistics in these countries have not been studied thoroughly. Country to "Dominion of Canada" or "Canadian Federation" or anything else please read the Talk Page ( Bengali: বাংলাদেশ inc-Latn Bangladesh) officially India, officially the Republic of India (भारत गणराज्य inc-Latn Bhārat Gaṇarājya; see also other Indian languages) is a country
- The rating of any given tornado is of the most severe damage to any well-built frame home or comparable level of damage from engineering analysis of other damage.
- The F6 level, although present in Dr. Ted Fujita's original wind scale, was not intended for use, is not an official damage level and is not used to rate tornadoes. There is, by definition, no such thing as an 'F6' tornado. [2]
| Category F0 | Estimated wind speed* | 40–72 mph | 64–116 km/h | Relative frequency | 38. (For the South African airport with IATA code "KMH" see Johan Pienaar Airport. 9% |
| Potential damage |
F0 damage example
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| Category F1 | Estimated wind speed* | 73–112 mph | 117–180 km/h | Relative frequency | 35. 6% |
| Potential damage |
F1 damage example
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| Category F2 | Estimated wind speed* | 113–157 mph | 181–253 km/h | Relative frequency | 19. 4% |
| Potential damage |
F2 damage example
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| Category F3 | Estimated wind speed* | 158–206 mph | 254–332 km/h | Relative frequency | 4. 9% |
| Potential damage |
F3 damage example
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| Category F4 | Estimated wind speed* | 207–260 mph | 333–418 km/h | Relative frequency | 1. 1% |
| Potential damage |
F4 damage example
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| Category F5 | Estimated wind speed* | 261–318 mph | 419–512 km/h | Relative frequency | Less than 0. 1% |
| Potential damage |
F5 damage example
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*Fujita's initial wind speed estimates have since been found to be highly inaccurate. See Enhanced Fujita Scale
Decommission in the US
The Fujita scale, introduced in 1971 as a means to differentiate tornado intensity and path area, assigned wind speeds to damage that were, at best, educated guesses. The Enhanced Fujita Scale, or EF Scale, is the scale for rating the strength of Tornadoes in the United States estimated via the damage they cause The Enhanced Fujita Scale, or EF Scale, is the scale for rating the strength of Tornadoes in the United States estimated via the damage they cause [3] Fujita and others recognized this immediately and intensive engineering analysis was conducted through the rest of the 1970s. This research, as well as subsequent research, showed that tornado wind speeds required to inflict the described damage were actually much lower than the F-scale indicated, particularly for the upper categories. Also, although the scale gave general descriptions for the type of damage a tornado could cause, it gave little leeway for strength of construction and other factors that might cause a building to receive higher damage at lower wind speeds. Fujita tried to address these problems somewhat in 1992 with the Modified Fujita Scale, but by then he was semi-retired and the National Weather Service was not in a position for the undertaking of updating to an entirely new scale, so it was a minor step. [4]
In the USA only, on February 1, 2007, the Fujita scale was decommissioned in favor of what these scientists believe is a more accurate Enhanced Fujita Scale, which replaces it. The EF Scale is thought to improve on the F-scale on many counts—it accounts for different degrees of damage that occur with different types of structures, both man-made and natural. The expanded and refined damage indicators and degrees of damage standardize what was somewhat ambiguous. It also is thought to provide a much better estimates for wind speeds, and sets no upper limit on the wind speeds for the strongest level, EF5.
The original Fujita scale is still used in most of the rest of the world, except where the TORRO scale is used. The TORRO tornado intensity scale (or T-Scale) is a scale measuring Tornado intensity between T0 and T11
See also
- Enhanced Fujita Scale
- TORRO scale
- Beaufort scale
- Saffir-Simpson Hurricane Scale
- Tornado intensity and damage
- List of tornadoes and tornado outbreaks
- List of F5 and EF5 tornadoes
- Severe weather terminology
References
- ^ Storm Prediction Center Enhanced Fujita Scale (EF Scale)
- ^ a b c Tornado FAQ. The Enhanced Fujita Scale, or EF Scale, is the scale for rating the strength of Tornadoes in the United States estimated via the damage they cause The TORRO tornado intensity scale (or T-Scale) is a scale measuring Tornado intensity between T0 and T11 The Beaufort scale (ˈboʊfət is an Empirical measure for describing Wind speed based mainly on observed sea conditions The Saffir-Simpson Hurricane Scale is a classification used for most Western Hemisphere Tropical cyclones that exceed the intensities of Tropical depressions Tornadoes vary in intensity regardless of shape size and location Tornado events These are some notable Tornadoes Tornado outbreaks and Tornado outbreak sequences that have occurred around the globe This is a list of all official rated and authoritatively Severe weather terminology is different around the world varying between regions and countries Storm Prediction Center. Site accessed June 27, 2006. Events 1358 - Republic of Dubrovnik is founded 1709 - Peter the Great defeats Charles XII of Sweden Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar.
- ^ Fujita, Tetsuya Theodore (1971). was a severe storms researcher of the twentieth century Born in Kitakyushu, Fukuoka Prefecture, Japan, he studied at Kyushu Institute of Technology Proposed characterization of tornadoes and hurricanes by area and intensity. Chicago: University of Chicago.
- ^ Fujita, Tetsuya Theodore (1992). was a severe storms researcher of the twentieth century Born in Kitakyushu, Fukuoka Prefecture, Japan, he studied at Kyushu Institute of Technology Memoirs of an Effort to Unlock the Mystery of Severe Storms. Chicago: University of Chicago.
- Marshall, Timothy P. (2001). Tim Marshall (b October 17, 1956) is a Civil engineer and Meteorologist concentrating on damage analysis particularly that from Wind "Birth of the Fujita Scale". Storm Track. Storm Track was the first Magazine for and about Storm chasing. 24 (3): 6-10.
External links
- NOAA National Weather Service Improves Tornado Rating System (NOAA News)
- Enhanced F Scale for Tornado Damage (SPC)
- The Enhanced Fujita Scale (EF Scale) {SPC)
- Fujita Scale Enhancement Project (Wind Science and Engineering Research Center at Texas Tech University)
- Mitigation Assessment Team Report: Midwest Tornadoes of May 3, 1999 (FEMA)
- A Guide to F-Scale Damage Assessment (NWS)
- A Guide for Conducting Convective Windstorm Surveys (NWS SR146)
- The Tornado: An Engineering-Oriented Perspective (NWS SR147)
- The Fujita Scale of Tornado Intensity (The Tornado Project)
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