Purpose: To inform the audience about tornadoes.
A. Attention getter: What can throw tractor trailers threw the air like matchbox cars, rip homes to shreds and travel at speeds near 400 MPH? B. Audience motivation: There are approximately 10 Air Force bases located in or very close to tornado alley. Knowing the different types of tornadoes and what to do if one occurred near you may potentially save your life. C. Credibility: I lived in the heart of tornado alley for 16 years and have personally experienced at least 30 tornadoes. D. Thesis Statement: The purpose of this presentation is to inform the audience on tornadoes. I will inform them on what a tornado is by definition, what causes a tornado, the types of tornadoes and tornado safety.
A. According to the Encyclopedia Britannica the definition of a tornado is a violent, low-pressure storm, relatively small in diameter but with very rapidly rotating winds and an intense updraft near the centre. B. What causes a tornado
i. The USA Today Information site states that tornadoes form in unusually violent thunderstorms when there is sufficient instability and wind shear present in the lower atmosphere. Meaning, severe thunderstorms are the first step in the creation of a tornado. ii. The same source defines instability in a thunderstorm as an unusually warm and humid condition in the lower atmosphere and cooler than usual conditions in the upper atmosphere. Wind shear refers to the wind direction changing and wind speed increasing with height. An example would be a southerly wind of 15 mph at the surface, changing to a southwesterly or westerly wind of 50 mph at 5,000 feet. iii. I mentioned in the introduction that quite a few Air Force bases were located in tornado alley. [VISUAL AID] More tornadoes occur in this area because cold air from the west and north clash violently with warm air from the Gulf of Mexico.
Transition: Know that you have a better understanding about what causes tornadoes, let twist through the types of tornadoes.
C. Types of tornadoes
i. [VISUAL AID] The first and most common type of tornado is a supercell tornado. These tornadoes are more likely to remain in contact with the ground for long periods of time. They can remain on the ground for an hour or more and are likely to be very violent, with wind speeds reaching 200 mph or more. ii. [VISUAL AID] The second type of tornado I will discuss is the landspout tornado. This type is generally weaker than a supercell tornado. It is not associated with a mesocyclone, which is what most people know as a wall cloud. It is the land equivalent to a waterspout tornado. Winds speeds for this type of tornado usually don’t exceed 125 mph and are short lived. iii. [VISUAL AID] The next type of tornado is the firewhirl tornado. According to weather.com these are created by a major forest fire or volcanic eruption. They are tornado-like rotating column of smoke and/or fire. Winds associated with firewhirls have been estimated at over 100 MPH. iv. [VISUAL AID] The last type of tornado we will go over is the waterspout tornado. This type of tornado is more often than not, a lot less intense and causes much less damage. It is usually less than 50 yards wide. It forms over warm tropical waters and is made of fresh water from condensation, not salt water from the ocean.
Transition: Now that we crashed through the types of tornadoes, let go through what you should do if one of the above tornadoes was to touch down near you.
D. What to do if involved in a tornado
i. Tornadoes have occurred at least once in each month, so any time is a good time to review tornado safety procedures-for home, in the car, and while out and about. ii. Tornado Project Online reports that the one most important thing you can do to prevent being injured by a tornado is to stay ALERT to the onset of severe weather. Most deaths and injuries happen to those that are unaware. iii. Be alert to what’s happening outside. If you are in either a tornado warning or a watch then the fall of hail should be considered a real danger sign. The sky will likely be greenish or greenish black before a tornado and a strange quiet usually happens right before a tornado touches ground. iv. According to Tornado Project Online the safest place to take shelter in your home is: in a storm shelter, in a basement away from the west and south walls or in a small, windowless, first floor interior room like a closet or bathroom. If your in your car or out and about the best place to seek shelter would be the basement of any building, but if need be lying flat in a ditch or low-lying area maybe the only thing available. Do not try to outrun a tornado in your car; you never know what you may run into. Many people have been killed trying to outrun a tornado. v. The main point to remember about tornado safety is, you must be aware of your surroundings. If the weather outside is getting crappy, you should probably turn on the TV or radio to see what’s actually going on. Finally you want to remember to put as many barriers as you can between you and the tornado.
A. In this presentation I have gone over the definition of a tornado, what causes tornadoes, the types of tornadoes and what you should do if involved in a tornado. B. If you’re ever in tornado alley during the months of March-May and you hear sirens go off, you’ll know what to do to either keep yourself or your family safe from this nasty piece of Mother Nature called a tornado.
“Tornado.” Encyclopedia Britannica Online. 2010. Encyclopedia Britannica. 3 Dec 2010.
Tornadoes are earth’s most violent storms. Sept. 2006. USA Today. 4 Dec 2010
Types of Tornadoes. May 2003. The Weather Channel. Weather.com. 4 Dec 2010.
"Tornado." Columbia Electronic Encyclopedia, 6th Edition (2010): 1. Academic Search Premier. EBSCO. Web. 21 Nov. 2010.
“Safety.” 1999. Tornado Project. 4 Dec 2010.