Tornadoes are one of the most destructive weather events on Earth. In fact, the fastest winds observed near the Earth’s surface occur within the strongest tornadoes! Tornado damage can range from “minor” damage, where small trees, loose objects and shingles on roofs are blown off, to “incredible” damage, where essentially everything within a tornado’s path is destroyed.
It is very difficult to directly measure the strongest wind speeds within a tornado. While radar imagery can be used to sometimes get somewhat of a wind estimate, the metric used to estimate tornado wind speed maxima is the Enhanced Fujita (EF) scale (named after the scientist Dr. Ted Fujita in 1971 (originally called the “F-Scale”). The image above shows the different EF-Scale ratings, which are assigned to a tornado after National Weather Service employees assess the damage caused after a tornado impacts a region.
In this activity, you will explore the variables that directly affect tornado strength and predict how severe tornado damage is within a series of simulations.
Part 1 – Tornado Formation
To start with, watch this video regarding how tornadoes form:
Then, take a look at this website here.
Question 1: Discuss with your breakout group what you learned from the tornado formation video as well as from the website link. Type anything interesting you learned in the text box below, and also be ready to share what you learned with the rest of the camp!
Part 2 – The EF Scale
Watch this video from The Weather Channel explaining the tornado EF-Scale:
A Tornado Hits The Weather Channel
Then, check out the following links:
EF-Scale explained (this will help with Part 3 of this activity)
Assessing tornado damage to determine tornado EF rating
Question 2: Discuss with your breakout group what you learned from The Weather Channel video as well as from the website links provided. Type anything interesting you learned in the text box below, and also be ready to share what you learned with the rest of the camp!
Part 3 – Assessing Tornado Damage on Your Own!
For the final part of this exercise, you will assess tornado damage and learn how tornado size and pressure difference between the inside and outside of a tornado is related to tornado strength. To do this, use the applet at the link here. Answer the following questions below while checking out the applet.
Question 3: First, try out a simulation with the default settings (Funnel width = 560 yards and Pressure diff = 0.6 in Hg; Rotating speed = 100 mph). Run the simulation by clicking “Go”. What EF-rating best applies in this scenario?
Question 4: Next, repeat the simulation, however make the tornado as wide as possible (you’ll have to click the “reset” button first in order to change the settings). Then, click “Go”. What EF-rating best applies in this scenario?
Question 5: Next, repeat the simulation (don’t forget to click “reset” first!), however this time make the tornado as narrow as possible AND make the pressure difference (or wind speed maximum) as large as possible. Then, click “Go”. What EF-rating best applies in this scenario?
Question 6: For this final question, work with your group to determine a funnel width/pressure difference combination that leads to each of the EF-scale tornado types. Within the text box below, write down what combination you used to create each EF-scale type (EF-0, EF-1, EF-2, EF-3, EF-4, EF-5).