Experiment #3: How to create tornado in a bottle?

What is a tornado?

Wikipedia defines tornado as "A tornado is a violently rotating column of air that is in contact with both the surface of the earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. They are often referred to as twisters or cyclones,although the word cyclone is used in meteorology, in a wider sense, to name any closed low pressure circulation."

My son and I decided to create a tornado in a bottle. We can replicate the effect on a smaller scale with simple items like dish washing liquid, glitters, water and bottle. 

Aim: To create tornado in a bottle using simple kitchen items

Things needed:

1. 1 glass bottle
2. Water to fill it 3/4 th or less
3. Glitters ( I bought this at Walmart)
4. Dish washing liquid 
5. Funnel

Method:

1. Set up the working area. I used a plastic tray to catch the spills.
2. Fill the bottle with water (3/4th or less)
3. Add few drops of dish washing liquid
4. Place the funnel in the neck of the bottle, ask the kid to sprinkle lots of glitter into it (More glitter in the water, more visible will be our tornado in a bottle)
5. Tightly screw the cap to the bottle. Check well so there is no leaks
6. Turn the bottle upside down and hold it by the neck. Spin the bottle in circular motion for some time, about 10-20 seconds, stop and look at the mini tornado forming in the water. 
7. We had to try it few more times to get it right. So keep swirling it and sing to your child for each round you make:

"Round and round the garden

Like a teddy bear

One step, two step

Tickle under there"

What actually happens?

When you spin the bottle in circular motion, it creates a water vortex. You will see water spinning around the center of the bottle. This is due to centripetal force. It is an inward force which directs the object (in this case water) towards the center of its circular path.  This effect looks like a mini tornado.