Informative Speech #2
 
By Christina Kjar, Section 36, 2/22/99

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Specific Purpose Statement: At the end of my speech, my audience will be more aware of the characteristics of a tornado.

Introduction:

I. When I was about ten years old, my parents and I were going on a day trip to the Danish Villages.

A. There were large clouds in the sky, and for some reason I asked my mom if they could make tornadoes.
       1. Of course she said, "No."
B. As we came over the large hill, I could see that the cloud I was watching had changed.
       1. It had turned into a funnel cloud.
C. We turned around and headed home.

D. That "harmless" cloud turned into a terrible tornado that went through the town that day.

E. Ever since then, I have been fascinated with tornadoes.

II. Throughout my speech, you will learn many things you need to know about tornadoes such as:
A. How they form,
B. When they occur,
C. And how to detect them.
III. By the end, you'll be more aware and informed in case a tornado happens to come your way.

Body:

I. A tornado is the most violent storm nature produces.

A. A tornado starts when a funnel-shaped cloud hangs down from the sky but doesn't touch the ground.

B. When the cloud hits the ground, it's known as a tornado.

C. Tornadoes form in cumulonimbus clouds.

       1. These are commonly known as thunderstorms.

       2. The tornado is in the SW part, while the heavy rain is in the NE.

D. The inner part of the tornado is known as the vortex.

       1. This is composed of intense, circulating air around a central core.

       2. When viewed from above, it rotates counterclockwise.

E. According to John Stanford, there are 3 main ingredients needed for a tornado to occur.

       1. Warm air with an abundant supply of moisture is needed in the lowest level of the atmosphere.

       2. Another layer of cooler and dryer air lays above the lowest level.

         a. This causes instability.

       3. Finally, the jet stream needs to be at a high altitude.

II. There are many specific characteristics that accompany all tornadoes
A. Heavy hail and downpours precede and follow the tornado.

B. There is lots of intense lightening, which helps to spot on at night.

C. Supersonic winds can cause a loud noise resembling the roar objets or trains.

III. Even though tornadoes take on many of the same characteristics, their appearances can differ greatly.
A. One appearance is the difference in shape.

      1. The tornado can either be irregular and wide

      2. or very smooth and rope-like.

B. The color of a tornado can also be very different. It depends on 2 things:
 
      1. The background that it's viewed against

      2. and the material brought up from the surface.

C. According to the background...

      1. if it has a dark rain behind it, it appears white.

          a. The tornado is then moving NE.

      2. If there are clear skies behind it, it appears dark

          b. It is then moving SW.

D. Depending on the type of soil brought up, the dust surrounding it can appear brown, yellow, or red.

E. Electrical charges can also give it a "glow."

IV. Tornadoes occur more frequently in some parts of the U.S. than others.
A. Tornado Alley is a section of the United States that stretches north from Texas to Iowa, as defined by The Weather Channel.

       1. This area receives the most tornadoes.

       2. Most occur in April, May, and June.

B. According to Flora Snowden, who is the author of "Tornadoes of the United States, the record number of tornadoes occurring in 1 year was 1,109 in 1973, which caused 87 deaths."

C. There is an average of 708 per year, with an average of 93 deaths and many more injuries.

       1. Iowa averages about 100-200 yearly.

         a. Most occur in the month of May

         b. and happen from 4-6 p.m.

 D. The typical Midwest tornado is...

       1. on the ground for 30 minutes,

       2. covers 15 miles,

       3. and leaves a damage strip 300 yards wide.

E. However, a tornado can occasionally stay on the ground for 200 miles and  have a damage strip over a mile wide.

V. Tornadoes and wind storms are classified on the Fujita Scale, which is located  in The World Almanac and Book of Facts.
 
          A. It was created by T. Theodore Fujita.
B. There are 6 ranks to the scale.

       1. Each is based on the amount and type of wind damage.

       2. The lowest is F-O and the highest is F-5.

C. As you can see by the chart, each rank has its own wind speed, damage level, and strength of the storm.

D. For example, if a tornado came through Cedar Falls and was classified as an F-3...

       1. It would have wind speeds from 158-206 mph,

       2. Severe damage,

       3. and a strong strength.

VI. Last, but certainly not least, the ways to detect tornadoes.
                1. Sometimes you can hear the loud noise of a tornado as it approaches.

              2. Because of the enormous amount of extra lightening, your t.v. can often get fuzzy.

              3. Farm animals or pets can have odd behavior.

              4. Finally, the clouds can take on a greenish tint.

Conclusion:

I. Throughout my speech, I covered a variety of topics about tornadoes.

A. Whether it was weather conditions,

B. types of tornadoes,

C. or different detection strategies.

II. So, if you happen to be outdoors around supper time in May and a storm is brewing, keep watch and don't be surprised if a tornado develops.

III.  Maybe you'll become as fascinated as I did.

IV. Thank you.
 

Works Cited

  Eagleman, J. (1975). Thunderstorms, Tornadoes, and Building Damage. Lexington Books.

  Flora, S. (1953). Tornadoes of the United States. University of Oklahoma Press: Norman.

  Stanford, J. (1987). Tornado: Accounts of Tornadoes in Iowa. (2nd ed.) . Ames: Iowa State University Press.

The World Almanac and Book of Facts: 1997. (1996). Richard W. Eiger.

WWW.WEATHER.COM. The Weather Channel Homepage.