You will need two plastic bottles (any size will do, but same size works best) and some water to make your bottle-bound tornado.
Half fill one bottle with water and screw on the Whirlpool. Then screw the second empty bottle into the other side of the valve. Turn the bottles so that the one with water is upside down and watch what happens. The water flows slowly into the bottom bottle.
Now try it again, this time giving the bottles a quick swirl around in a circle. This time the water flows much faster, and a vortex forms. This funnel-like structure allows the air from the bottom bottle to rise quickly and smoothly. You can add food colouring and glitter to the water to make it easier to see the vortex.
