TORNADO IN A BOTTLE
Knight Foundation Summer Institute
Lisa Nelson, Wagner Middle School
Emily Dorean, Haverford College
Introduction:
Early this summer, parts of Texas and several other southern states were severely hit by tornadoes. These huge disasters wreaked havoc on several towns, as we saw on the news. This coverage and call to respond and help those communities to recover provided a very timely opportunity and reference for investigating tornadoes in a classroom.
A tornado is a natural storm disaster created when a front of hot, humid air and a front of cool, dry air collide in the atmosphere. The warm air is pushed upward, which causes winds carrying water droplets to rotate into a vortex, speeding at up to 300 mph in the center. This spinning column of air and water droplets then begins to stretch between the earth and a convection cloud (made up of water droplets) to create a tornado. The water droplets form from the condensation of water vapor in the area within the funnel where there is low temperature and pressure. This makes the funnel visible to our eyes, because the large number of water droplets block out the sun's light, just like a thunder cloud.
In this lab, you will be able to see what a tornado looks like on a very small scale. This experiment shows water moving through a small hole in a manner that simulates the spiraling behavior of the tail of the tornado. The condensation funnel, or tail, causes great destruction for anything in its path, as it touches the earth and sweeps objects and debris up into its vortex (the spinning center). You will be able to analyze this phenomenon and describe some of its characteristics using this model.
Objectives:
1. To learn how scientists can use a model of a tornado to better understand the processes of nature.
2. To critically design the best set-up for this experiment using the materials available.
3. To have a broader view of how tornadoes affect a place, not just physically, but culturally as well.
Vocabulary:
Condensation
convection current
tornado
vortex
(For reference and definitions for weather vocabulary, see the web site
www.weather.com , and
www.nssl.uoknor.edu . Both resources have clear definitions.)
Materials:
* 2 cleaned-out 2-Liter plastic bottles per cooperative group (other types of bottles will also work, especially for testing to create the most effective set-up).
* 1 roll of duct tape
* 1 pen per student
* water
* scissors
* paper towels
Procedure:
Divide students into cooperative groups, and give each group two bottles. They can then:
1. Remove labels from the plastic bottles.
2. Cut a 3" x 3" piece of duct tape, and make a hole in the middle of it with the pen. (The size of the hole should be determined by the student, after they have written in their lab notebook their own hypothesis about what they think will work best to create a tornado effect in the bottle. I found that it works fine with no tape, although the demonstration is rather short. The smaller the hole, the more tight the spiral tail will be.)
3. Position the tape with the hole over the mouth of the bottle, and secure tightly around the sides. (See attached diagram.)
4. Fill the other bottle three-quarters (3/4) of the way with water (I also tried adding little bits of debris to make it look more close to a real-life simulation, and this worked all right, although the pieces must be extremely small).
5. Place the two mouths of the bottles together (the empty one upside-down on top of the water-filled one), and tape them carefully together with the duct tape, making sure not to leave any holes. Test for leakage by carefully rotating the bottles.
6. To create the tornado affect, turn the bottles upside-down so that the water should be flowing through the hole into the bottom, empty bottle. Swirl slowly to help create the funnel.
7. Repeat this procedure using different materials and techniques, such as different bottles, liquids, and swirling techniques, and compare the different effects between the set-ups. Look at the size of the hole in the bottle, and the difference in the vortex. Is there a change in speed in the swirling water, depending on the size of this hole? Is the swirling funnel more stable with different set-ups?
Assessments:
Discuss the different tornadoes created by the class, and talk about what could make a tornado better or worse. How is a tornado created? Why does it stop? What determines its direction?
Have each cooperative group write up a mini lab report, in which they compare their individual tornado bottles, and relate their final set-up to their initial set-up plans (see Procedure #2).
As a wrap-up project, have each student (or pair of students, if it is unlikely that each student can write their own small essay) research a tornado that has occurred in the past 5 years. They should write a brief description of where it happened, and what effects it had on the structures, people and communities in which it touched down. This information can be found in the national newspapers from the last 5 years (accessible on microfilm or microfiche in most public and college libraries, or over the World Wide Web), in some of the back issues of Scholastic News and other student magazines, or on the web at:
www.weatherlabs.com , or
my.excite.com
Extensions:
This works well in an interdisciplinary setting integrating weather with literature. (There is a super book available that integrates teaching physical sciences through children's literature. This can be found at
www.books.mcgraw-hill.com ) Another suggestion is to have the students write their own fictional stories about a tornado experience, incorporating the vocabulary and the concept of the tornado structure. Film clips from Twister and The Wizard of Oz would also be fun and appropriate!
There are several experiments on air pressure that are directly related to tornadoes (see the lab "The Magic Balloon", in this packet) through the change in air pressure that is associated with this type of storm. It may be interesting to note that houses found near a tornado have exploded, due to the huge decrease in air pressure surrounding the house. The higher pressure air inside the house then pushes on the walls with a huge force. Experiments that engage in further inquiry about this subject can be found in several of the resources listed within this booklet, as well as at the website:
www.miami.sci.org
Philadelphia Science Content Standards:
SCIENCE CONTENT STANDARD 1: NATURE OF SCIENCE
This experiment satisfies Benchmark 1 for grades 5-8: "design, modify, and conduct and investigation through testing, revising, and occasionally discarding ideas, all of which lead to a better understanding of how things work.''
This experiment also satisfies Benchmark 3 for grades 5-8: "collect and summarize data from an experiment and interpret the results in terms of the data."
SCIENCE CONTENT STANDARD 2: PHYSICAL SETTING
This experiment backs up the concepts found in Benchmark 2 for grades 5-8: "understand that the earth is a constantly changing and moving system as indicated by\ crustal plates, weather, etc."
SCIENCE CONTENT STANDARD 7: HISTORICAL PERSPECTIVES
This experiment touches on Benchmark 3 for grades 5-8: "demonstrate that technology is increasingly important in spreading ideas and discoveries within and among diverse cultures", because students need to learn and be aware of how technology has changed the warnings for tornadoes, and how this has changed the effects of these natural disasters on different cultures and places.
Cross-references:
This lab has many cross-references, but most especially to history and writing. As I suggested above, activities for assessment, as well as interdisciplinary work, can include writing a short adventure story, reading and reporting on fictional books and factual articles about tornadoes, and working on projects of the historical import of tornadoes in our country. See the lab Volcano! In this packet for more ideas.
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