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Weather Experts

What causes tornadoes? Learn about tornadoes and wind speed as you build your own anemometer and a tornado in a jar!

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Plan

  • What are some examples of extreme weather?
  • How can we prepare for extreme weather?
  • What does an anemometer measure?
  • What supplies will you need for this activity?
  • Will you do this experiment on your own, in pairs or in small teams?

Do

Tornado in a Jar

  • Fill your jar about 3/4 full with water and add in 3-5 drops of blue food dye (depending on the size of your jar and how dark you want the water to be).
  • Add a teaspoon of dish soap and a teaspoon of vinegar to your blue water.
  • Tighten your lid
  • Hold the jar by the lid and rotate it around in a circle in a smooth, steady motion with your wrist and watch the vortex form.

Anemometer

  • Make a hole in the side of each of the 4 paper cups.
  • Make 4 holes spaced evenly around the rim of the last cup. This will be the center of the anemometer.
  • Slide 2 of the wooden dowels through the holes in the center cup. They should cross in an “X.”
  • Insert the ends of the dowels into the holes of the other cups and tape them into place. Make sure the cups are all facing the same direction.
  • Take the last wooden dowel and make a hole in the bottom of the center cup.
  • Push the dowel up until it meets the X and tape everything together. This will be your rotation axis.
  • Put the center dowel into an empty water bottle and begin testing!

Testing Your Anemometer

  • Start by calibrating your anemometer. Check the wind speed outside (a weather website should be able to help with this) and bring your anemometer outside. Count how many times your anemometer rotates in 30 seconds. You now know how many times your anemometer will rotate in 30 seconds at the current wind speed.
  • Alternatively, you can ask an adult to drive you in a car going 10km an hour. Put the anemometer out the window and count how many times it rotates in 30 seconds.
  • Now you know how much it will rotate at a given wind speed. You can use that number to figure out how fast the wind is going, based on how quickly your anemometer is spinning.

Review

  • What do you know now that you did not know before?
  • How could measuring air speed help you when planning adventures?
  • How are air speed and tornadoes connected?

Materials

Tornado in a Jar

  • 1 jar with a lid per person, pair or small group
  • Water
  • Blue food dye
  • Liquid dish soap
  • White vinegar

 

Anemometer

  • 5 small paper cups per person, pair or small team
  • Hole punch
  • 3 wooden dowels per person, pair or team
  • Tape
  • Empty water bottle
  • Stopwatch for testing (a phone stopwatch is fine)

Keep it Simple

  • Make a tornado in a jar in Lairs or Patrols. You can add glitter to the jar before you seal it, as it will make the tornado easier to see. Talk about what happens when tornados form and why we have to be careful if tornados are spotted nearby.

Take it Further

  • Put your anemometer to use and track wind speed over time. Use your anemometer to track wind speed on a daily basis. Do you notice any patterns?