Example research essay topic: Wind Speed Air Masses - 1,748 words

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Tornado Every year approximately one thousand tornados happen in the United States, which annually kill about 60 people (Wikipedia). Tornadoes are classified as the most dangerous and destructive types of storms. They bring a lot of damage, especially to our country, which experiences the most amount and the most intense tornadoes on earth. Tornado is a vortex of spinning air with very low pressure, rising to the cloud in atmosphere. It touches the ground and causes physical damage when moving across the surface of earth. Tornado can be observed as a windstorm in the shape of funnel, which moves in any direction and can last from few minutes up to few hours.

Usual speed of the rotating wind of a tornado can reach 100 mph, and in the hardest cases it can grow up to 300 mph. As to the speed of tornado movement, it varies from 15 to 50 miles per hour. Usually, it is supposed that rotating thunderstorm super-cells cause tornadoes and other types of storms. In the cases, when cold air masses happen to lay upper than cold air masses do, certain energy forces the warmer layers of air to rise extremely rapidly. As the speed of the wind is permanently increasing, movement of the airflow's becomes circular, and they start spinning in the atmosphere. This development continues within the time.

The center of tornado funnel is the area of the lowest pressure, so when a new flow of air reaches the center of the funnel, pressure grows higher and cools the air. That is how water vapor, which forms tornado cloud, is condensed in the air. As the described process is fast and constant, tornado cloud moves horizontally and continues its rotation. Actually, the nature of formation of tornado funnel is a very complex and not totally understood issue. The reasons of tornado dissimilation are also still debatable. It is supposed to be that sooner or later a tornado comes under the influence of some air outflows.

These outflows are relatively cold and large, so they cause instability in the movement of tornado and slightly calm it down. In the majority of cases such outflows are formed by other thunderstorms, but not always. Usually a tornado can be formed only on the edge of the updrafts, thats why it is frequently accompanied with hail or heavy rain. Only special climatic conditions, like temperature, level of moisture, pressure, etc.

may cause formation of tornado during a thunderstorm. In many cases climatic conditions are not favorable for developing spinning whirlwinds, so storm does not take dangerous form of tornado or hurricane. The main parametric characteristics of tornado are its diameter, which is usually varies from 20 to 100 meters, its duration and range of action. Usually a tornado can move across the territory of about 5 - 150 square miles. Also, there are two principal physical characteristics of tornadoes, wind speed and intensity of tornado. They can help to find out, what are the effect and strength of this type of windstorm.

In order to estimate the intensity, a special table called The Fujita Scale was developed by Dr. T. Theodore Fujita (available in Appendix 1). This system classifies 7 types of tornadoes by their intensity, starting from the weakest (gale and moderate tornadoes) and ending with the strongest (incredible and inconceivable tornadoes). The scale derives the intensity from the information about wind speed, and also presents description of the damage done by one or another type of tornado. Notable fact is that intensity is not dependent on size and width of tornado vortex.

Therefore, if a funnel is wide, it does not mean that the tornado is very intensive and violent. Certainly, probability of tornado occurrence is directly connected with geographical and climatic conditions. Those geographical territories, which can be characterized with unstable airflow's, low and mid-level humidity in the atmosphere, or with other indicators of unbalanced microclimate, are the most probable areas of tornado occurrence. Mostly such areas are located in tropical and subtropical zones. In the United States tornados can happen at any location, especially during the period from April to June. The territories, where the most regular tornadoes usually happen, are states of Oklahoma and Texas.

There are more than 100 considerable tornados are recorded in Oklahoma City since 1890 (Edwards). The strongest and the most devastating tornadoes occur in Massachusetts, which has the highest indexes of death from this type of windstorm. In 1953 a number of tornadoes in this state resulted in death of 94 people, and during 1999 36 people became victims of this natural disaster (Wikipedia). In the USA overwhelming majority of the tornadoes happen because of mixing of cold polar Canadian winds with warm moisture's air masses, which are coming from southern regions and Mexico.

Specialists could notice that there are territories in our country, where tornado occurrence is very high. This zone is called Tornado Alley and is located in the Midwest and South of the country (covering Texas, Nebraska, Iowa, Colorado, Oklahoma, Kansas, and other states). Tornado Alley remains under precise control and supervision of storm and weather forecasting specialists. The other geographic areas, which are forming tornado risk zone, are Canada, Australia and New Zealand, Japan and Southern Africa, some territories of Southern Asia, Spain, Germany and the United Kingdom, etc. According to the research of Fujita Scale Class, more than 75 % of total amount of tornados are weak, about 25 % are strong and only 1 % are violent. But, at the same time, violent tornados caused 67 % of total amount of deaths, strong tornados brought 29 % of deaths and weak tornados brought 4 %. (Fujita) It is a very important point for our country to forecast tornadoes and be aware of all the measures, which should be taken in case of tornado threat.

In the United States such an organization as National Weather Service (NWS) is doing the main researches on tornado forecasting. Storm Prediction Center, a department of NWS, issues special weather studies and particular tornado forecasts. Besides it offers other services, regarding to probability of tornado occurrence. The principal ones of them are so called tornado watches and tornado warnings. A tornado watch marks the territories, which are the most likely to undergo a tornado or a storm in the next few hours. A tornado watch only reports about probability of tornado, so it informs populace of such marked areas about the necessity to get ready for possible storm.

A tornado warning is a message about already spotted tornadoes or about very probable ones. After receiving a tornado warning, all the people of the stated locality have to take all precautions and expect some really hard weather conditions soon. Also, everybody has to be familiar with the main principles of safety during a storm. Any citizen of the USA has to be informed in time about the possibility of approach of tornado, and everybody has to be well aware, what to do and where to hide in such situation. This issue is very important for our country, as there is always quite a big threat of tornado almost everywhere in the United States. Nowadays ecological situation on earth is growing radically worth.

This year our country suffered a number of devastating hurricanes of high level of danger, like Katrina, Rita and Wilma, which have been raging around Atlantic region of the United States for more than two months. They killed thousands of people, left hundred thousands without a roof over the head, and brought damage for millions UDS. That is why in such conditions it becomes essential to research, study and know all the details about possible types of storms, especially for those Americans, who live in Tornado Alley. Unfortunately, the opportunities of human intervention into the process of forming and development of a tornado or a hurricane are rather minimal. But, in anyway, there are still a lot of activities, which can be directed on prevention of numerous victims and saving lives of people during any type of storm. Appendix 1 Table 1.

The Fujita Scale of Tornado Intensity. F-Scale Number Intensity Phrase Wind Speed Type of Damage Done F 0 Gale tornado 40 - 72 mph Some damage to chimneys; breaks branches off trees; pushes over shallow-rooted trees; damages sign boards. F 1 Moderate tornado 73 - 112 mph The lower limit is the beginning of hurricane wind speed; peels surface off roofs; mobile homes pushed off foundations or overturned; moving autos pushed off the roads; attached garages may be destroyed. F 2 Significant tornado 113 - 157 mph Considerable damage. Roofs torn off frame houses; mobile homes demolished; boxcars pushed over; large trees snapped or uprooted; light object missiles generated. F 3 Severe tornado 158 - 206 mph Roof and some walls torn off well constructed houses; trains overturned; most trees in forest uprooted F 4 Devastating tornado 207 - 260 mph Well-constructed houses leveled; structures with weak foundations blown off some distance; cars thrown and large missiles generated.

F 5 Incredible tornado 261 - 318 mph Strong frame houses lifted off foundations and carried considerable distances to disintegrate; automobile sized missiles fly through the air in excess of 100 meters; trees debarked; steel re-informed concrete structures badly damaged. F 6 Inconceivable tornado 319 - 379 mph These winds are very unlikely. The small area of damage they might produce would probably not be recognizable along with the mess produced by F 4 and F 5 wind that would surround the F 6 winds. Missiles, such as cars and refrigerators would do serious secondary damage that could not be directly identified as F 6 damage. If this level is ever achieved, evidence for it might only be found in some manner of ground swirl pattern, for it may never be identifiable through engineering studies Source: The Fujita Scale (retrieved from < web >) Bibliography: Cappella, Chris. "Tornadoes Are Earths Most Violent Storms. " USA Today. Garnett Co.

Inc. 20 Feb. 2004. 9 Nov. 2005 < web >. Edwards, Roger. "Frequently Asked Questions about Tornadoes. " Storm Prediction Center. NOAA National Weather Service. 21 Oct. 2005. 9 Nov. 2005 < web >. Rosenberg, Matt. "Tornado. " About. New York Times Company. 9 Nov. 2005 < web >. "The Fujita Scale of Tornado Intensity. " Tornado Project. 9 Nov. 2005 < web >. "Tornado. " Wikipedia. The Free Encyclopedia Online. 7 Nov. 2005. 9 Nov. 2005 < web >.

Research essay sample on Wind Speed Air Masses