Will tornadoes increase because of global warming? I get asked this all the time. While the scientists debate what is causing the changes in our climate, many fear global warming will cause an increase in tornadoes. So are we seeing an increase in tornadoes due to global warming? That is a complicated question. Many factors must be researched to determine if global warming would increase tornadoes. Does a higher global temperature make for stronger or weaker low pressure systems? Does it make for stronger or weaker Jet stream? Does a warmer earth add more wind shear to the environment or lessen it? Will warmer temperatures decrease dew points or increase them? What effects will a warmer earth have on not just surface temperatures, but will temperatures aloft increase also. What effect will this have on thunderstorm development and capping? Will there be more high pressure system over the land masses if the earth is warmer? To better understand how warmer weather effects tornado frequency you will need to study the cause of tornadoes in general.
There are a few actual measurements of tornado winds; their intensity is estimated through after-the-fact examination of the damage that they produced. Prior to February 2007, that was done using the Fujita Scale (F Scale). Since then, the National Weather Service has adopted an Enhance Fujita Scale (EF-Scale) to rate tornadoes. The original Fujita Scale was devised in 1971 by Ted Fujita, of the University of Chicago. It gave ratings of F0 to F5 based upon the type and severity of damage the tornado produced. At that time there were very few actual measurements of tornado wind speeds that he could relate to the damage, but he used them—together with a lot of insight—to devise approximate wind speed range of each damage category. In subsequent years, structural engineers have examined damage from many tornadoes. They use knowledge of the wind forces needed to damage or destroy various buildings and their component parts to estimate the wind speeds. They eventually determined the original F-Scale wind speed range were too high for categories F3 and higher.
The Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX) was designed to answer question about the cause of tornado formation. In 1994-1995, VORTEX successfully documented the entire life cycle of a tornado from beginning to end for the first time in history. Field operations took place in parts of Texas, Oklahoma and Kansas. VIORTEX was unique because field resources targeted a single storm each day to gather data over a supercell lifecycle. A team of investigators operated a dozen instrumented vehicles, two mobile laboratories, a Mobil Doppler radar and two Doppler-equipped aircraft. The more we learn about tornadoes and storms that can create them, the more they seem to become even more a mystery.
The word “Tornado” comes from the Latin tonare, meaning “to thunder”. The Spanish developed the word into tornear, to turn or twist. These are good descriptions of tornadoes, which are formed by rotating or twisting air. This is why they are also called twisters or cyclones. A tornado is a powerful column of winds spiraling around a center of low atmospheric pressure. It looks like a large black funnel hanging down from a storm cloud. The narrow end will move over the earth, whipping back and forth like a tail. The wind inside a tornado spiral upward and inward with a lot of speed and power. It creates an internal vacuum that then sucks up anything it passes over. When the funnel touches a structure, the fierce winds have the ability to tear it apart. The wind inside a twister can speed around at speeds up to 500 miles an hour, but usually travels at roughly 300 miles an hour. This makes the tornado the most dangerous storm known to mankind. Because of the earth's unique weather system, twisters rotate counterclockwise in the Northern Hemisphere and move eastward. They rotate clockwise in the Southern Hemisphere. Tornadoes also often come with hailstorms.
Many storms create harmless funnels that never touch earth. They can last from a few seconds to a few hours. Others disappear and reappear minutes later. The average tornado has a diameter of about 200 to 300 yards, and some grow large enough to spawn smaller tornadoes known as satellite tornadoes. These small offspring, about 50 yards across, can be very fierce and do lots of damage. They also tend to branch away from the parent funnel, taking separate paths across the earth. A tornado can form very quickly, sometimes in a minute or less. It can travel across the ground at high speeds, and then just as suddenly vanish. They can kill in a matter of seconds. Every year, about $500 million worth in damage is done by twisters in the United States. Most tornadoes last less than twenty minutes and travel less than 15 miles. However, super storms sometimes occur, traveling over 100 miles before they are exhausted. Although they don't occur very often, they are responsible for 20% of all tornado casualties.
Tornado conditions are caused when different temperatures and humidity meet to from thunderclouds. In the United States, warm, wet winds from the Gulf of Mexico move northward in spring and summer, meeting colder, dry Canadian winds moving southward. The place where these two winds meet is called the dry line. High, dry air coming from the north piles on top of low-moving, moist Gulf air at a height of over 10,000 feet. The warm southern winds try to raise but the cold northern air block them. This clash causes the warm, trapped air to rotate horizontally between two masses. At the same time, the sun heats the earth below, warming more air that continues to try and rise. Finally, the rising warm wind becomes strong enough to force itself up through the colder air layer.
When this occurs, the cold air on top begins to sink, sending the rising warm wind spinning upward. The warm winds rotate faster and faster in a high column. When the updraft is strong, the column can rise to heights of 10 miles or more, twisting at speeds of up to 100 miles an hour. The rotating winds produce strong storm clouds about 70,000 feet high, sometimes spreading 10 miles wide. This storm system may stay intact for several hours, at which point its thunderclouds are known as supercells. These storm clouds can send down an inch of rain in a mere ten minutes or shower the ground with baseball-sizes hailstones. Supercells can accumulate into huge clusters, forming a line almost 100 miles long, which can then develop into mesocyclones.
The mesocyclones is the “mother of tornadoes”. It is a spine of wind that gradually narrows and spins more and more fiercely vertically through the supercells. A wall of clouds swirls with it, making it visible to the human eye as a huge, black cloud bulging down from the supercell thunderclouds. It can be anywhere from half a mile to six miles wide (almost the height of Mt. Everest!). Mesocyclones do not always produce tornadoes. About 1,700 mesocyclones strike the United States every year, but only half produce tornadoes. If the cyclone runs out of wet, warm surface ground and may become a giant tornado. Observers have found that tornadoes are likely to form when the clouds look yellow or green, or when the air is muggy and still after rain and hail has stopped. Tornadoes appear on the right rear side of supercells, taking place where a stream of cool air from the downdraft twirls into the main warm air updraft. Mesocyclones can also drop many tornadoes at once, which spin around the mother funnel like spokes around a central wheel. On February 19, 1884, one such storm brought 60 tornadoes in the same day.
Waterspouts. A waterspout occurs when a tornado form over the oceans, lakes, or rivers. They form when high layers of cool air blow across a body of water while warm moist air sweeps up from below. They appear as thin columns with the funnels sucking up water over mushroom- shaped water sprays. Waterspouts can vary in size from a few feet to more than a mile in height, and from a few feet to hundreds of feet wide. Witnesses say they make hissing and sucking noises as they move. These water twisters can move anywhere from 2 to 80 miles an hour. Winds within the waterspouts can spiral around at 60-120 miles an hour. Similar to tornadoes, waterspouts are often seen in groups. Ships out on the ocean have reported as many as 30 in one day. Waterspouts, like their land counterparts, can pick up and transport some interesting objects. In Montreal, a waterspout once carried lizards and rained them on the hapless Canadians. They have sent showers of tadpoles in New York, and even toads in France. One in Province, Rhode Island, rained fish down on the people, who promptly collected and sold them. Waterspouts appear most often from May to September over warm ocean water. They are usually not as dangerous as tornadoes, but can still cause serious damage to ships. The Litian Morris, a sailing ship, struck a 500-foot-wide waterspout that tore its masts, sails, and swept a man overboard. Waterspouts sank five ships at Tunis, on the North African coast, in 1885.
Tornadoes have been known to give off lightning sparks. During one twister in Oklahoma, about 24,000 lightning flashes were recorded. Scientists think that these electrical discharges may be the real force that drive tornadoes. Lightning between clouds appear strongest when the mesocyclone reaches its peak. It has been described as more brilliant, bluer, and more “vicious” than normal lightning. Witnesses have described the sound of a tornado as a “sustained, hollow can feel the sound vibrating the air against their faces.
roaring, like a distant freight train”. Others say they hear strange hissing, whistling noises, while others claim they sound like hundreds of locomotives, thousand of cannons, or the buzzing of a million bees. Some people even say they
Tornado behavior is never precisely predictable. The funnel may or may not touch the ground, touch and vanish, touch, rise, and touch again, move in circles, spin in one spot for 20 minutes, or cut zigzags through the countryside. When a tornado does touch the earth, its neck can measure from 50 yards to as wide as one mile. It usually moves about 40 miles an hour, cutting a path of destruction 2 miles wide. The tornado's shape can also differ, looking like a long, thin rope or an upside-down bell. The length from the base of the funnel to the tip of its “trunk” can be from 800 to 2,000 feet. Faster upper winds usually blow the top of the funnel more quickly than the lower portion, making the tail seem to drag behind. Earth friction also adds to the lag.
A . The fajita Scale
B. The Verification of the Origins of Rotation in Tornadoes Experiments (VORTEX)
C. The Verification of the Origins of Rotation in Tornadoes Experiments (VORTEX 2)
D. Storm Chasers
A. The Fujita Scale: Also known as the Fujita-Pearson Scale may not be a perfect system for linking damage to wind speed, but it had distinct advantages over what had gone on before its inception. And it was simple enough to use in daily practice without involving additional expenditure of time or money. From a practical point of view, it is doubtful that any other system would have found its way into widespread accepted use, even to this day. The entire premise of estimating wind speed from damage to non-engineered structures is very subjective and is difficult to defend from various meteorological perspectives. Nothing less than the combined influence and prestige of the late Professor Fujita and Allen Pearson, director of NSSFC (National Severe Storm Forecast Center) in 1971 could brought this much needed system into widespread use. The FPP scale rates the intensity of the tornado, and measured both the path length and the path width. The Fujita Scale is based on damage, not the appearance of the funnel. The Fujita Scale is very subjective, and varies according to how experienced the surveyor is.
B. VORTEX (1994-1995): It was designed to answer questions about the causes of tornado formation. VORTEX successfully documented the entire life circle of a tornado from beginning to end for the first time in history. Field operation took place in part of Texas, Oklahoma and Kansas. VORTEX was unique because field resources targeted a single storm each day to gather data over a complete supercell lifecycle. A team of investigators operated a dozen instrumented vehicles, two mobile laboratories, a mobile Doppler radar and two Doppler-equipped aircraft. VORTEX scientists found that the leading edges of pools of cooler air left behind by thunderstorms are prime locations for later tornado formation. They also discovered tornado formation seems to be linked to the character and behavior of the “rear-flank” downdraft at the back- side of the supercell storm. Surprisingly, it appear fewer supercells and mesocyclones produce tornadoes than scientists believed, with only subtle differences occurring between tornadic and non-tornadic mesocyclones. Subsequent smaller field efforts based on these discoveries focused data collection on the storm's small hook echo region. The goal of this ongoing work is to determine those types of rear-flank downdrafts that support tornado formation and those that hinder or prevent it.
C. VORTEX 2 (2009-2010): It is the largest and most ambitious field experiment in history to explore tornadoes. VORTEX 2 is supported by National Oceanic and Atmospheric Administration (NOAA) and the National Science Foundation (NFC). Nearly 100 scientists and students from sixteen different universities and various other academic organizations in the United States are expected to take part in the experiment. VORTEX 2 will also involve forecasters from the NOAA National Weather Service (NWS) forecast offices, the NOAA Storm Prediction Center, Environmental Canada, the Australia Bureau of Meteorology and Finland. The VORTEX 2 teams will be looking to understand how, when and why tornadoes form. Answers to these questions will give researchers a better understanding of tornadoes and should help increase warning time for those path of these deadly storms.
D. Storm Chasers: The NSSL, sends out teams of scientists to chase storms and study them. The teams locate and intercept the twisters, keeping in touch by radio and mobile phone. Their vans are fully equipped with computer-controlled electronic equipment, remote-control video cameras, and sensitive detention systems. At first, these teams dropped a 400- pound barrel called TOTO (Totable Tornado Observatory) in the path of a tornado. This device measure the twister's wind speed, temperature, direction, and atmospheric pressure. However, the TOTO was usually blown over as soon the storm winds reached 150 miles an hour. Starting in 1987, it has been replaced by a Doppler radar unit with a range of 3 to 5 miles. This new device can identify a mesocyclone two or four hours before it develops into a tornado. It also knows weather tornado winds are moving toward or away from it and how fast. More recently, Next-Generation Weather Radar systems have been introduced, which track and analyze mesocyclones better than ordinary radar. A second radar network called Profilers can also measure winds in the upper atmosphere, 20 miles above the earth. These can help predict possible mesocyclones, and will work with weather balloons to give wind direction and speed at different altitudes. When twisters have actually been seen or detected by radar, it is the local weather stations responsibility to issue the tornado warnings. Warnings are sent out as quickly as possible over TV and radio, reporting areas in danger, times of detention, and expected strikes. The weather stations can see the tornadoes on radar, as a revolving “6” shape dangling down from a mesocyclone image. Warnings are crucial, even if they are given a few minutes before the disaster strikes. It can mean a few precious seconds between life and dead.
E.Preparation: The best way to protect against tornadoes is a well-build house, strong enough to withstand fierce winds. Engineers recommended wall of reinforced concrete, well-anchored to a foundation. A solid roof can also be secured with strap anchors over the rafters. Many of the people in Tornado Alley who don't have strong houses have built storm cellars. Storm cellars of this kind should be separate from the house, located near the southwest corner of the building, and not too close to the house walls. The doors should open inward in case debris block the exit, and should have a good drainage system to prevent flooding. A tactic once used to reduce tornado damage was to open a building's windows, equalizing air pressure inside and outside. However, new studies suggest it is better to keep all windows closed against tornadoes. It is advised to keep extremely alert after a tornado watch has been issued, especially if the weather is very humid, and oppressive, with dark thunderclouds in the western and northern sky. Even if you live outside “Tornado Alley”, the area of the country that runs north from Texas through eastern Nebraska and northern Indiana, you are still vulnerable to tornadoes. Kansas, Oklahoma and Texas may see more of these unpredictable and dangerous storms than other states, but the rest of the country also gets its share of twister.
Throughout history, humans have been amazed and intrigued by the various forces of nature, particularly those associated with weather. This fascination can most readily be attributed to the fact that so many different weather patterns exist throughout the world. This diversity in climates results in a wide range of weather conditions; from relatively calm weather to dangerously violent storms. Despite the great variation in weather patterns among the world's many climates, tornadoes are one weather phenomenon that have been known to occur in almost every climate on Earth. Because a tornado is one of the world's most deadly forces of nature, it is important for humans to strive to understand what tornadoes are, how they are formed, their potential dangers, and how to better predict the formation of tornadoes so that effective warming can be issued.
In order to completely understand the dangers of tornadoes, it is important to examine the current explanations for how and why tornadoes form. Tornadoes are most often generated by supercell storms. Supercell storms are particularly large, severe storms that develop in highly unstable environments in which cool, dry air lies above warm, moist air. Supercells typically from the United States during the spring as warm, moist air from the Gulf of Mexico flows north and comes in contact with cooler, dryer layers of air. The Midwestern section of the United States tends to be the location for the majority of the country's tornadoes. Because of this, the area from the Gulf of Mexico to the Great Lakes, spanning over one thousand miles wide, is referred to as “tornado alley”.
Although the number of tornadoes reported in the United States each year may seem rather high, in actually only one percent of the thunderstorms make tornadoes. Of the total number of tornadoes recorded each year, on average, seventy-nine percent are considered to be weak, twenty percent are rated as strong, and one percent is recorded as violent. Although tornadoes appear mostly in the United States, they have been reported worldwide. It is evident that tornadoes are not isolated to the tornado alley of the United States, but do occur in all different types of regions all over the earth.
Once it is understood of how and why tornadoes form, the next step is to attempt to predict their behavior. Due to strength of the winds within a tornado, the path that it takes may highly unpredictable. The tornado may move in a circular motion or turn to the left or to the right.
Due to their extremely high wind speed, tornadoes have the ability to cause a great deal of damage, but they also have been known to produce some extremely unusual events. They are known to carry cars and even houses miles. And leave people homeless and without any belongings on the street. Because some tornadoes appear to be more damaging than others, a system has been created to rate these storms according to their size of their path. The fujita Scale rank tornadoes according to their speed and the size of their path. The scale range from F-0 to F-5 (F-0 being least destructive and F-5 being most destructive). An F-0 tornado causes light damage to chimneys, shallow-rooted trees, and sign boards. In the middle of the scale, an F-2 tornado causes considerable damage by tearing roofs off frames houses, demolishing mobile homes, snapping large trees, and carrying light objects. On the most destructive end of the scale, an F-5 tornado causes incredible destruction. Such tornadoes can lift strong frames houses off their foundations and carry them considerable distances to disintegrate, carry automobile-sized objects through the air for hundreds of feet, and even de-bark trees.
With the help of modern technology, meteorologists and weather researchers have gotten a lot more experience in the area of tornado forecasting. Through satellite images meteorologists have made it possible to detect the shape of the clouds. Knowing the shape and the type of the cloud system that produces a storm help meteorologists to predict whether or not a tornado will be produced. This method of tornado monitoring has been useful in the past. However, the most effective method of monitoring severe storms is the use of Doppler radar. It measures wind speeds by bouncing microwaves off air. Doppler radar is proving to be a valuable tool in predicting the formation of tornadoes. Using radar images of a storm, meteorologists can identify rotation within clouds thirty minutes before a tornado will emerge. Forecasters issue tornado warnings at the first sign of a developing tornado. This gives the public more time to be ready for the tornado to touch down.
The Optical Transient Detector (OTD) was invented in 1995, by NASA. This was the first invention able to detect lightning events during both day and night. It job was to detect and increased number of clouds to cloud lightning flashes. The OTD was able to detect more lightning passes from cloud to cloud than between clouds and Earth just before tornadoes are made. Its limitations are that its only use is that it's only able to find tornadoes only moments before they hit the ground. The OTD technology, however, is useful in that it can detect the formation of a tornado much quicker than Doppler radar.
The Verification of the Origins of Rotation in Tornadoes Experiments (VORTEX) was designed to answer questions about the causes of tornado formation. VORTEX successfully documented the entire life cycle of a tornado from beginning to end for the first time in history. Field operations took place in part of Texas, Oklahoma and Kansas. VORTEX was unique because field resources targeted a single storm each day to gather data over a complete supercell lifecycle. This first phase of VORTEX, conducted in 1994-1995, resulted in well documented advances in our understanding of the kinematic similarities between tornadic and non tornadic supercell thunderstorms and the implied sensitivity of supercells and tornadogenesis to fine-scale heterogeneity, both pre-storm and storm-induced. Recent improvements in National Weather Service warning statistics may be attributable in part to the application of VORTEX findings pertaining to the important role of the near-storm environment in determining potential for tornado formation.
Despite the broad successes of VORTEX, many new questions have emerged regarding the circulation sources for tornadoes, the role of downdraft and thermodynamics in tornado genesis, the dynamics of the tornado itself, and the relationship between tornadoes and large scales of motion. These questions are described in the accompanying VORTEX 2 Scientific Program Overview (SPO). Significant technological advances have occurred since VORTEX 1, including notable advances in ground-based mobile Doppler radars and the ability to obtain thermodynamic observations using ground-based and near-ground platforms. These advances have increased not only the ability to resolve small spatial and temporal scales within thunderstorms, but also the mobility of data-collecting fleets and the ability to target storms.
VORTEX 2 will take full advantage of cutting-edge remote and in situ observing systems, including radar data collection from moving ground-based platforms, in situ tornado probes for profiling wind and state data, and in situ observations obtained from remotely-piloted aircraft. Furthermore, VORTEX 2 includes the application of data assimilation techniques to determine better the atmospheric state. VORTEX 2 will occur during mid to late spring, statistically the most active time of year for severe weather. Storms tend to be slower moving at this time of the year, presenting a better opportunity for observation.
The more we learn about tornadoes and storms that can create them, the more they seem to become even more of a mystery. It is possible that some insight we have yet to find will help in our understanding of tornadoes. On the other hand, new research may not result in a quick understanding, but may raise new and even more confusing issues scientists will have to deal with. Until the many questions about tornadoes are answered, tornadoes will remain one of the mother nature's biggest destructors.