Geology Home Page physical geology historical geology planetary gems
Roger Weller, geology instructor
by David Munoz
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 warnings 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 form in 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 actuality only one percent of all 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 are 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 the 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 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 destructive potential. The Fujita scale ranks tornadoes according to their speed and the size of their path. The scale ranges from F0 to F5 (F0 being least destructive and F5 being most destructive). An F0 tornado causes light damage to chimneys, shallow-rooted trees, and sign boards. In the middle of the scale, an F2 tornado causes considerable damage by tearing roofs off frame houses, demolishing mobile homes, snapping large trees, and carrying light objects. On the most destructive end of the scale, an F5 tornado causes incredible destruction. Such tornadoes can lift strong frame 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 helps 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 rain, dust, and other objects in the air.
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. Its job was to detect and increased number of cloud 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 its only able to find tornados only moment 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 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 Mother Nature’s biggest destructors
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