The NTEN Home Page The NTEN Home Page About the National Teachers Enhancement Network Read Answers to Frequently Asked Questions Log In To WebCT Resources for Effective Online Teaching
Testimonials By Our Students Tour A Sample Online Class
Go to the NTEN Science Resources Our Online Course Offerings Kit-Based Learning for Elementary School Teachers
   

Lesson Plan: Hurricanes and Tornadoes
Subject: Earth and Space / Meteorology / Storms
Classtime:Total: 3 class periods (50 minutes each)
Grade Level: 5-12

Materials/Technology:

  • a computer with adequate memory to run an Internet connection
  • one computer for each group of two students (recommended)
  • a server that allows access to the Internet
  • basic computer skill so user can log on to the Internet

Safety, Handling, Disposal:
Close supervision is strongly recommended when students are conducting searches on the Internet. Inappropriate sites are easy to access either by mistake or on purpose.

Learner Outcomes:
Students should be able to:

  • Explain the difference between a tornado and a hurricane.
  • Explain how tornadoes and hurricanes are classified.

Problem/Purpose:
What are the differences between tornadoes and hurricanes; and how are each of them classified?

Background/Inquiry:
 The information below came from this web site:

  • University at Buffalo: State University of New York: School of Engineering and Applied Sciences: http://www.civil.buffalo.edu/wind/windinf2.html (obsolete)

Tornadoes are spawned by thunderstorms. A variety of mechanisms give rise to thunderstorms; therefore, storms behave somewhat differently in the various climatological regions of the nation. All types can occasionally become severe. A thunderstorm is officially considered severe if it produces a tornado, winds in excess of 58 mph (26 m/s), or surface hail greater than 0.75 inch (20 mm) in diameter.

A tornado can produce the highest wind speeds known. This swirling column of air is usually associated with a severe thunderstorm, though its location beneath the storm can vary. A worldwide phenomenon, tornadoes occur most often in the United States. From 1953 through 1989, about 27,000 tornadoes were documented in the United States. Tornadoes are concentrated in the central half of the country and are most prevalent in parts of the states of Texas, Oklahoma, and Kansas (though on a whole-state basis, Indiana ranks ahead of Kansas).

Tropical cyclones. A few times each year, from early June through October, low-pressure systems (termed tropical cyclones) form over warm ocean waters in the tropics. Occasionally, where sea-surface temperatures are greater than 22o C (72o F.) and when winds high in the atmosphere are supportive, one of these systems will become more organized and intensify to become a hurricane (wind speeds exceeding 73 mph (64 knots) or more (Anthes, 1982)).

When fully developed, a hurricane has a calm, central core, or eye, surrounded by very strong winds concentrated in a doughnut-shaped region of heavy rain, termed the eyewall. A pattern of rainbands, each consisting of many thunderstorm cells, spirals inward to merge with the eyewall. These violent tropical cyclones tend to be self-sustaining until they move either into a region of sea-surface temperatures less than 26.5o C (80o F) or over land. In either case, the system is cut off from its main energy source, the warm sea surface.

The eastern and Gulf coasts of the United States are threatened by tropical cyclones that form in the tropical Atlantic and in the Gulf of Mexico. From 1931 through 1987, 551 tropical storms were observed in these areas; 314 of these reached hurricane status. In an average year, about four tropical storms will make landfall in the continental United States; on average, two of these will be hurricanes. The actual number of hurricanes per year in the subtropical northern Atlantic, Caribbean, and Gulf of Mexico has shown wide variability, ranging from 2 (1931, 1983) to 12 (1969).

Vocabulary List: Here.

Hypothesis:
Example: There are no major differences between tornadoes and hurricanes.

Procedure:

  1. Students log onto the Internet and enter the following URL:
  2. Read the text and answer question #1 in the Results/Analysissection.

    3. *Note: The following are expected student answers:

    1. A large amount of warm humid air.
    2. Low level winds that shift directions and grow stronger just above the ground.
    3. Lack of "competition" from nearby storms.
  3. Enter the following URL:
  4. After the page has completely downloaded, place the cursor over image #1. Watch the animation and read the text to the right.
  5. Place the cursor over image #2. Watch the animation and read the text to the right.
  6. Place the cursor over image #3. Watch the animation and read the text to the right.
  7. Click on the Fujita wind damage scale rates tornadoes link (used to classify tornadoes).
    • After the page loads, click on F-0 link, then scroll to the top of the page. This will give a description of the scale and what it is based on. Read the descriptions of the F-0 through the F-6 classifications.
  8. Students log onto the Internet and enter the following URL:
  9. Study the image and read the text below the image.
  10. Click on the what hurricanes need to grow link.
  11. Read the text and answer question #2 in the Results/Analysis section.

    12. *Note: The following are expected student answers:

    1. Ocean water above 80° F in a layer at least 200 feet deep.
    2. Winds coming together from different directions, which forces air upwards over the warm water. The air up to 18,000 feet above the ocean surface needs to be humid to supply adequate moisture.
    3. Upper atmosphere high pressure above the growing storm. The air in this high flows outward which encourages more air to rise from the surface. A hurricane´s winds are caused by the air near the ocean surface rushing in to replace the rising air.
  12. Enter the following URL:
  13. Read the text describing the Saffir-Simpson damage potential scale (used to classify hurricanes). Note the additional categories of atmospheric pressure and storm surge that are not on the Fujita Tornado Scale.
  14. Click on a Category 1 link and read the text.
  15. Scroll to the top of the page and click on the Storm Surge link.
  16. After the page has completely downloaded, place the cursor over image #1. Watch the animation and read the text to the right.
  17. Place the cursor over image #2. Watch the animation and read the text to the right.
  18. Scroll down the page and read the text on storm surge. Answer question #3 in the Results/Analysis section.

Results/Analysis:

  1. What three main factors are needed to form a tornado?
  2. What three main factors are needed to form a hurricane?
  3. What causes a storm surge?
  4. What is the Fujita wind damage scale for tornadoes based on?
  5. What is the Saffir-Simpson damage potential scale for hurricanes based on?

Conclusions:
Students write a conclusion to answer the question posed in the Problem/Purpose. Use the answers from Results/Analysis section above as a guide.

Assessments: (if included)
Compare the factors causing tornado formation to those required for a hurricane to form.

What are the major differences between the Fujita scales for tornado damage and the Saffir-Simpson hurricane damage scale.

Integration: (if included)
Students write a report highlighting the impact of a specific storm on people living in areas affected by them.

Reflections:
Share your thoughts on this lesson with the NTEN team.

Please send an e-mail to Patti Harrison.

Extensions: (if included)
Students go to the USA Today home page and track a current hurricane or tornado.

References/Resources: (if included)

Credits
Contributing Teacher: Tim Tharp
NTEN Course: Internet-Based K-14 Earth Systems Science Instruction
Instructor: Jerry Nelson
Assistant Instructor: Bill Ochs
Developing Team:
T.L. Buck Buchanan, Cathy Hensel, Patti Harrison, John Usher, Don Wilson
HTML Programmers: Christy Cousineau, John Usher, Ching-Kwong Chia

Copyright © 1998 - 2002, National Teachers Enhancement Network
Comments: pattih@montana.edu

Up to Top

    
www.scienceteacher.org