Tornado Intensity can be measured by in situ or remote sensing measurements, but since this is not practical for wide-scale use, intensity is usually summed up through proxies, such as damage. Fujita's scale and Fujita's level of scalability are enhanced by the damage caused. The Fujita Scale upgrade is an upgrade to the older Fujita scale, with estimated winds being engineered (by expert estimates) and better damage descriptions, but designed so that the tornadoes rated on the Fujita scale will receive the same numerical rating. An EF0 tornado will probably damage the tree but not substantial structures, whereas EF5 tornadoes can tear buildings from the foundations they leave them naked and even damage large skyscrapers. The same TORRO scale ranges from T0 to very weak tornado to T11 for the most powerful tornado. Doppler radar data, photogrammetry, and circular patterns (cycloidal signs) can also be analyzed to determine intensity and ratings.
Tornadoes vary in intensity regardless of shape, size, and location, although strong tornadoes are usually larger than weak tornadoes. The relationship with the length and duration of the track also varies, although longer tracks (and longer life) tornadoes tend to be stronger. In the case of a cruel tornado, only a fraction of the road area is the intensity of violence; most of its intensity is higher than subvortis. In the United States, 80% of tornadoes are EF0 and EF1 tornadoes (T0 to T3). Incidence rates dropped rapidly with increased strength - less than 1% were violent tornadoes (EF4, T8 or stronger).
Video Tornado intensity
History of the measurement of the intensity of the tornado
For years, before the advent of the Doppler radar, scientists were nothing more than guessing about the wind speed in a tornado. The only evidence that shows the wind velocity found in tornadoes is the damage left by tornadoes that hit densely populated areas. Some believe they reach 400 mph (640 km/h); others think they may exceed 500 mph (800 km/h), and may even become supersonic. One can still find false assumptions in some of the old literature (until the 1960s), such as the original Fujita Intensity Scale developed by Dr. Tetsuya Theodore Fujita in the early 70s. However, one can find accounts (eg [1] make sure to scroll down) some of the extraordinary work done in this field by US Army troops, Sergeant John Park Finley.
In 1971, Dr. Tetsuya Theodore Fujita introduced the idea to scale the tornadoes. With the help of colleague Allen Pearson, he created and introduced what came to be called the Fujita scale in 1973. This is what stands for F in F1, F2, etc. This scale is based on the relationship between the Beaufort scale and the Mach number scale; the low end of F1 on the scale corresponds to the low end B12 on the Beaufort scale, and the low end F12 corresponds to the speed at the surface of the sea, or Mach 1. In practice, the tornado is only given category F0 through F5.
The TORRO scale, created by the Tornado and Storm Research Organization (TORRO), was developed in 1974 and published a year later. The TORRO scale has 12 levels, covering a wider range with tighter graduation. These range from T0 to very weak tornadoes to T11 to the most powerful known tornadoes. T0-T1 is approximately corresponding to F0, T2-T3 to F1, and so on. While T10 is approximately F5, the highest tornado assessed to date on the TORRO scale is T8. There is some debate about the usefulness of the TORRO scale on the Fujita scale - while it may be useful for statistical purposes to have more tornado strength levels, often the damage caused can be created by winds, rendering it difficult to narrow down the tornado into a single TORRO scale category.
Research conducted in the late 1980s and 1990s shows that, even with the implications of the Fujita scale, the famous tornado wind is too high, especially in significant and loud tornadoes. Therefore, in 2006, the American Meteorological Society introduced an enhanced Fujita scale, to help set realistic wind speeds against tornado damage. The scientists specifically designed the scale so that the tornadoes were rated on the Fujita scale and the Fujita Enhanced scale would receive the same rank. The EF scale is more specific in detailing the extent of damage to different types of structures for specific wind speeds. While the F-scale goes from F0 to F12 in theory, the EF scale is limited to EF5, which is defined as "wind> = 200 mph (320 km/h)". In the United States, the scale-up of Fujita took effect on February 2, 2007 for the assessment of tornado damage and the Fujita scale is no longer in use.
The first observations confirmed that F5 winds could occur on 26 April 1991. A tornado near Red Rock, Oklahoma was monitored by scientists using portable Doppler radar, an experimental radar device that measures wind speed. Near the peak of tornado intensity, they recorded wind speeds of 115-120 m/s (260-270 mph). Although portable radar has uncertainty Ã, Â ± 5-10 m/s (11-22 mph), this reading may be in the F5 range, confirming that tornadoes are capable of strong winds not found elsewhere on earth.
Eight years later, during the 2003 Oklahoma tornado rupture on May 3, 1999, another scientific team was monitoring a very violent tornado (which would eventually kill 36 people in the Oklahoma City metropolitan area). At around 19:00, they recorded a measurement of 301 Ã, Â ± 20 mph (484 Ã, Â ± 32Ã, b/h), 50 mph (80 mph/hr) faster than previous records. Although this reading is only short of the theoretical F6 rankings, measurements are made over 100 feet (30 m) in the air, where wind is usually stronger than on the surface. In a tornado rating, only the surface wind velocity, or wind speed indicated by tornado damage, is taken into account. Also, in practice, F6 rank is not used.
While scientists have long theorized that very low pressure can occur at the center of a tornado, there is no measurement to confirm it. Several barometers of the surviving house pass close to the tornado, registering values ​​as low as 24Ã, inHg (810Ã, hPa), but these measurements are highly uncertain. However, on June 24, 2003, a group of researchers managed to drop a device called a "tortoise" into a F4 tornado near Manchester, South Dakota, one of which measures a pressure drop of more than 100 hPa (3.0 Â ° inHg) as the tornado passes. directly overhead. However, tornadoes vary widely, so meteorologists are still doing research to determine if these values ​​are typical or not.
Maps Tornado intensity
Typical intensity
In the United States, tornado accounts F0 and F1 (T0 to T3) account for 80% of all tornadoes. Incidence rates decline rapidly with increased strength - violent tornadoes (stronger than F4, T8), accounting for less than 1% of all tornado reports. Around the world, powerful tornadoes cause a smaller percentage of the total tornado. Cruel tornadoes are rare outside the United States, Canada and Bangladesh.
Tornadoes F5 and EF5 are rare, occur on average every few years. An F5 tornado was reported in Elie, Manitoba in Canada, on June 22, 2007. Prior to that, the last confirmed F5 was the 1999 Bridge Creek-Moore tornado, which killed 36 people on May 3, 1999. Nine EF5 tornadoes have occurred in the United States, at Greensburg, Kansas on May 4, 2007; Parkersburg, Iowa on May 25, 2008; Smithville, Mississippi, Philadelphia, Mississippi, Hackleburg, Alabama and Rainsville, Alabama (four separate tornadoes) on April 27, 2011; Joplin, Missouri on May 22, 2011 and El Reno, Oklahoma on May 24, 2011. On May 20, 2013 another confirmed EF5 tornado struck Moore, Oklahoma.
Typical damage
A typical tornado has winds of 110 mph (180 km/h) or less, about 250 feet (76 m), and travels one mile (1.6 km) or more before it disappears. However, tornadic behavior varies greatly; these numbers represent only statistical probabilities.
Two tornadoes that look almost exactly the same can produce very different effects. Also, two highly visible tornadoes can produce similar damage. This is due to the fact that tornadoes are formed by several different mechanisms, and also that they follow a life cycle that causes the same tornado to change in appearance over time. People on the tornado path should not try to determine their strength as they approach. Between 1950 and 2014 in the United States, 222 people have been killed by EF1 tornadoes, and 21 people have been killed by EF0 tornadoes.
Weak tornado
The majority of tornadoes are called EF1 or EF0, also known as "weak" tornadoes. However, weak is a relative term for a tornado, because even this can cause significant damage. Tornadoes F0 and F1 are usually short-lived - since 1980 nearly 75% of tornadoes rated weak live on the ground for 1 mile (1.6 km) or less. However, at present, they can cause damage and loss of life.
The damage of EF0 (T0-T1) is characterized by shallow structural and vegetation damage. Well-constructed structures are usually unscathed, sometimes damaged in windows, with minor damage to roofs and chimneys. Billboards and big boards can be torn down. Trees may have large branches that are broken, and may be uprooted if they have shallow roots. Any tornado that is confirmed but does not cause damage (ie remains in the open field) is always rated EF0 as well.
Damage to EF1 (T2-T3) has caused more fatalities than those caused by EF0 tornadoes. At this level, damage to the mobile home and other temporary structures becomes significant, and other cars and vehicles can be pushed out of the way or reversed. Permanent structures can be severely damaged on the roof.
Tornado significant
Rob2 (T4-T5) tornadoes are the lower end "significant" but stronger than most tropical cyclones (although tropical cyclones affect much larger areas and their winds last for longer durations). Well-constructed structures can suffer serious damage, including roof loss, and the collapse of some exterior walls can occur in poorly constructed structures. The car house, however, was totally destroyed. Vehicles can be lifted off the ground, and light objects can be small missiles, causing damage outside the main tornado path. The forested areas will have a large percentage of their jolted or uprooted trees.
EF3 damage (T6-T7) is a serious risk to life and limbs and the point at which tornadoes are statistically becomes much more destructive and deadly. Only parts of the affected buildings are left standing; well-constructed structures lose all the outside and some inner walls. Unfarmed homes are washed away, and houses with bad holders can collapse completely. Small vehicles and similar-sized objects are lifted off the ground and thrown as projectiles. Forested areas will suffer almost total loss of vegetation, and some tree debarking may occur. Statistically speaking, EF3 is the maximum allowable level for residential dwellings that are effective enough in place in the first floor interior space closest to the home center (the most extensive tornado protection procedure in America for those who do not have underground or underground shelters ).
Malignant tornado
While separate examples there are people who survived the impact of E/F5 in their homes - one of the survivors of Jarrell F5 is sheltered in the bath and magically blown up for safety when his home is destroyed - enduring the impact of E/F5 outside the strong and properly built underground storm shelters are statistically impossible.
EF4 damage (T8-T9) usually results in total loss of affected structure. Well-built homes are reduced to a pile of medium-sized debris on the foundation. Poor homes or no anchors will be swept away. Large, heavy vehicles, including airplanes, trains, and large trucks, can be pushed, reversed repeatedly or picked up and thrown. The big, healthy trees were entirely littered and thrown to the ground or completely overthrown and turned into flying projectiles. Passenger cars and similar-sized objects can be picked up and thrown for long distances. EF4 damage can be estimated even down to the most robust home level, making common practice for shelter in the interior space on the ground floor of the residence is not sufficient to ensure survival. Hurricane shelters, reinforced dungeons, or other underground shelters are deemed necessary to provide reasonable expectations about the safety of EF4 damage.
The damage of EF5 (T10-T11) represents the upper limit of tornado strength, and destruction is almost always total. An EF5 tornado attracts well-built homes and is well planted from their foundations and into the air before wiping them out, throwing debris for miles and wiping the foundations. Large and reinforced steel structures such as schools are completely flattened. Tornadoes of this intensity tend to tear and explore the lowland grass and vegetation from the ground. Very few identifiable structural debris is produced by EF5 damage, with most of the material reduced to a rough mixture of small, granular particles and spread evenly along the path of tornado damage. Large multi-ton steel frame vehicles and agricultural equipment are often mastered and emptied for miles or reduced entirely into unrecognizable component parts. This official description of the damage highlights the extreme nature of destruction, noting that "an extraordinary phenomenon will occur"; Historically, this includes an extraordinary display of power such as tilting skyscrapers, leveling the whole community, and stripping asphalt from the runway. Despite their relative scarcity, the damage caused by EF5 tornadoes shows extreme danger to life and extremities - since 1950 in the United States, only 58 tornadoes (0.1% of all reports) have been designated F5 or EF5, but these have the responsibility for more than 1300 deaths and 14,000 injuries (21.5% and 13.6%, respectively).
See also
- Tornado
- Tornado note
- Wind engineering
References
Further reading
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Feuerstein, Bernold; P. Groenemeijer; E. Dirksen; M. Hubrig; I. Holzer; N. Dotzek (June 2011). "Towards an increase in wind speed scale and description of the damage adjusted for Central Europe". Atmos. Res . 100 (4): 547-64. Bibcode: 2011AtmRe.100..547F. doi: 10.1016/j.atmosres.2010.12.026. < span> Ã,
Source of the article : Wikipedia
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