Name ___________________ Date ____ Class ____ _

Physical Geography of the United States and Canada

DiHerentiated Instruction

Tornado Alley A tornado is a violent, twisting column of air. It emerges from

within a thundercloud and reaches down to the ground. Tornadoes can come in many shapes, but they usually form in the shape of a funnel. Some have wind speeds of up to 450 miles (724 km) per hour.

Most tornadoes in the United States form in an area called "Tornado Alley." This area includes parts of several states, shown on the map below. Although tornadoes occur throughout the United States, especially along the Gulf Coast from Texas to Florida, people often think of the Great Plains when they hear about tornado activity. Tornado Alley

Why do so many tornadoes form in Tornado Alley? The most destructive tornadoes originate from strong, rotating thunderstorms called supercells. The geography of the Great Plains is a perfect breeding ground for supercells. The land in this region is relatively flat. This allows cold, dry, polar air from Canada to meet warm, moist, tropical air from the Gulf of Mexico. Most tornadoes form along the front-or meeting place-between these two air masses.

400 miles

Spring is the most active time for tornadoes. During this time of the year, tornadoes form mainly within Tornado Alley and east into the Ohio Valley. In summer, tornado activity moves mainly to an area extending from North and South Dakota into Pennsylvania and New York. Winter tornadoes usually form along the Gulf Coast. Tornadoes have been seen in alISO states.

Directions: On a separate sheet of paper, answer the following questions.

1. Identifying What is a supercell?

2. Theorizing Although tornadoes can form in any state, they rarely occur in the northeastern part of the United States. Why do you think this is so?

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-Teaching Strategies for Different Learning Styles

The following activities are ways the basic lesson can be modified to accommodate students' different learning styles.

English Learners (EL)

Ask students to define the term Tornado Alley [the area of the United States where most tornadoes occur], and have them explain the significance of the shaded part of the map. [The shaded section denotes Tornado Alley.] Also ask students if their community is located within Tornado Alley.

Verbal/Linguistic; Intrapersonal

A storm chaser is a person who intention­ally seeks out severe storms such as tornadoes. Many storm chasers simply want to see the event, though some are scientists who follow storms to conduct research. Storm chasing is particularly popular in the Great Plains. Ask students to prepare a report about this activity.

Visual/Spatial Assign students to create tornado-themed

art that depicts the power of the storm and typical geographic features found in Tornado Alley.

Kinesthetic Directions for creating "homemade torna­

does" are easy to find online. Allow students to make a "tornado in a bottle" and demon­strate it in class. Students should explain how their creations are similar to the storms that occur in Tornado Alley.

Logical/Mathematical

The Fujita Tornado Damage Scale is used to rate the intensity of a tornado. It examines the damage caused by a tornado after it has passed over a human-made structure. Ask students to create a table categorizing the different levels of the scale. Also ask them to create two circle graphs: one showing the percentage of all tornadoes since 1960 (or some other specific period) that were weak (FO-Fl), strong (F2-F3), or violent (F4-FS); and one showing the percentage of deaths caused by these levels of tornadoes. What conclusions

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can they draw from the data? (Roughly 74% of all tornadoes are weak, 25% are strong, and 1 % are violent- but 67% of deaths come from violent storms.)

Visual/Spatial

Tornado Alley has no agreed-upon bound­aries. The map accompanying the article is just one representation. Ask students to find and map another version of Tornado Alley based upon different criteria. Display students' maps in the class.

Advanced Learners

The April 3-4, 1974, Super Outbreak was the largest known outbreak of tornadoes in the United States, with 148 tornadoes forming in 11 states. Assign students to write a three-page report about this event.

Verbal/Linguistic; Interpersonal

Tornadoes have been prominently featured in a number of movies, stories, and songs. Divide the class into three groups, and have them use library or Internet resources to com­pile lists of as many of these as they can find. Share the lists in class to see who found the most.

Auditory/Musical

Invite students to compose a song that either (1) explains how tornadoes form, or (2) explains the steps to take in the event of a tornado. Allow students to perform their compositions in class.

Below Grade Level Ask students to use library or Internet

resources to find the difference between a tornado watch and a tornado warning. Have them explain the difference in a paragraph.