How to Make a Tornado in a Bottle
Tornadoes are formed when warm, moist air swirls together with cool, dry air. They are most often associated with storm clouds that contain vortexes — spirals of rising air. As the vortex sucks in the surrounding air, more air moves in at a high speed to fill the space.
1 Remove the labels from the bottles. Take the caps off each bottle and rinse the bottles thoroughly. Drill a 1/2 inch hole in the center of each cap. Kids should get an adult to help.
2 Place the caps together on their flat ends, and put a thin bead of caulk around the hole to seal it. Let it dry. Wrap a piece of duct tape tightly around the outside of the caps to stick them together.
3 Screw the caps back on to one of the 2-liter bottles. Fill the other bottle about 3/4 full with water. You can add food coloring and confetti if you would like. The confetti and food color helps to see the force of the vortex.
4 Twist the empty bottle tightly to the top of the bottle filled with water. Hold the bottles by the duct-taped area with one hand and use the other to support the bottom of the bottle.
5 Turn the bottles upside-down and stir them in a circular motion. You should see a vortex that forms as the water drains into the bottle on the bottom.
Watch Video Bottle Tornado.