Tornado in a Bottle

2 bottles of the same size – I used 2-liter bottles, but you can do this with smaller bottles too. The larger the bottles, the easier to see what’s happening inside, so I highly recommend using 2-liters.
bottle connector OR duct tape (Here’s a link to the bottle connectors I bought on Amazon. There are lots of options on Amazon and even more options on the Internet. These are just the ones I bought, that I can confirm work well)

Remove both caps from the bottles and the little ring around the opening. These can sometimes be tricky to get off, so I used a dull plastic knife to wedge under the ring. After stretching it a bit with the knife I could pry it over the grooves on the mouth of the bottle.
Fill one bottle 1/2 to 2/3 of the way full with water. If you want to add glitter or food coloring to make the tornado easier to see, now is the time. More on that below!
Connect the two bottles. If using duct tape, tape it very tightly so water won’t leak out. Use several layers of tape. If using the bottle connector, screw it onto the bottle filled with water, then turn the empty bottle upside-down and screw it into the top of the connector.

If you choose to go the duct tape route, you will need to redo the tape every couple of times you turn the bottles over. It works well, but it’s not a perfect seal, so some water will leak out.
You WILL want to practice this before doing the experiment in front of people. I’ve done this thousands of times and I still practice so I make sure it turns out right on the first try. Grab the middle where the two bottles connect with your hand upside down. If you extend your hand like you’re going to shake someone’s hand, turn it 180-degrees so your thumb is pointing to the ground. Grab the bottle, flip it upside down, and swirl in a counter-clockwise motion.

Rotation: this provides a clear example that can be repeated as often as necessary to demonstrate rotation of a tornado.
Debris: if you add glitter to the water, you can demonstrate how a tornado lofts debris into the sky. The glitter starts at the bottom of the bottle, but when you flip the bottles and spin them, the glitter will fly all around in the water. This looks a lot like how a tornado can loft debris from the ground into the sky and provides the chance to talk about why it’s so important to go to your safe place when a tornado is possible.
- Where is your safe place? Simply put: it’s the lowest level of your home with as many walls between you and the storm as possible. Avoid windows that can shatter. Bathrooms are generally safer because all the plumbing provides a little extra protection from the tornado. When going to your safe place, take something to protect your head (like a helmet) and shoes so you can safely get out if you have to walk through debris.
- Mobile homes are not a safe place to be in a tornado. You need to be in a structure that has a foundation in the ground.
- You should also know your safe place when at school and other places you go frequently.

Weather-school