Satellite image courtesy of NOAA
Springtime may bring the promise of April showers and May flowers. But it also brings the possibility of extreme weather, including violent thunder-storms and tornadoes.
Most countries experience tornadoes, but they occur more frequently in the United States, east of the Rocky Mountains, than anywhere else on Earth. On average, almost 1000 tornadoes touch down in the U.S. each year, leaving in their wake destruction and sometimes death.
How Tornadoes Form
Thunderstorms form when warm, moist air collides with an eastward moving cold front. These storms often produce strong winds, damaging hail, and even tornadoes. A tornado is a rapidly rotating column of air that extends from the base of a thunderstorm to the ground. A tornado’s characteristic funnel shape is visible because of water droplets, dust, and other debris that are caught up in the swirling air.
Measuring the Force of a Tornado
The force of a tornado is measured using the Fujita Scale, which ranks tornadoes based on the level of damage caused by the storm. The scale ranges from F-0 for a storm that causes light damage to F-5 for a storm that leaves incredible damage.
Mapping Tornado Frequency in the U.S.
a) Distribute to students copies of the handout. Have student examine the data in the handout to identify which states average the highest number of tornadoes each year.
b) Next, distribute blank U.S. maps. Have students construct choropleth maps showing the frequency of tornadoes by state in the U.S.
c) Explain to students that areas with a high occurrence of tornadoes have been given the nicknames of “Tornado Alley” and “Dixie Alley.” Have them refer to their maps to locate these two regions that experience many tornadoes each year.
Extending the Activity
Divide the class into three groups and assign each group one of the following research topics. When students have completed their research, have each group report back to the class.
i. Structure of a tornado
ii. Fujita Scale
iii. Tornado Alley/Dixie Alley
Watch the 2016 National Geographic Bee Finals
National Geographic Channel will air the final round of the National Geographic Bee Championship at 8 p.m. ET/PT on Friday, May 27. It will also air on public television stations; check local television listings for dates and times.
Join 11,000 schools and participate in this year’s National Geographic Bee. Get a notification to alert you when registration opens in August.
About the National Geographic Bee
Each year thousands of schools in the United States participate in the National Geographic Bee using materials prepared by the National Geographic Society. The contest is designed to inspire students to be curious about the world. Schools with students in grades four through eight are eligible for this entertaining and challenging competition.
The national championship preliminary rounds will take place on Monday, May 23, in Washington, D.C. The national championship final rounds featuring the top 10 finalists and moderated by humorist, journalist, and actor Mo Rocca will be held on Wednesday, May 25, at National Geographic’s Washington, D.C., headquarters.
The national champion will receive a $50,000 college scholarship, a lifetime membership in the National Geographic Society, and a Lindblad expedition to Southeast Alaska provided by Lindblad Expeditions and National Geographic.
Meet the 2016 Champions
National Geographic Bee contestants aren't just geography geniuses. They're also savvy park planners! See where they would create a National Park in their own state.
How to Help
Donations help fund schools to participate in the National Geographic Bee.
Teachers can use these activities in the classroom to prepare students for the bee!
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Springtime brings the possibility of extreme weather, including violent thunderstorms and tornadoes.