GIF by sundermier
For this experiment, you need two bottles of the same capacity and capsize, duct tape and water. You can also add food colouring or dyes to improve the appearance of the tornado.
First, fill up one bottle with water, if you’ve got any dyes add them to the water to improve visibility and make the tornado colourful.
Once the bottle is ready, use the duct tape to attach the empty bottle onto the full bottle such that the water flows from the full bottle into the empty bottle when the full bottle is placed upside down and no air can escape between the two bottles.
Now place the empty bottle on the table so that the full bottle is draining the water into the empty bottle. Quickly, give the full bottle a whirl so that the water spins as it drains but make sure you provide support to the duct-taped area while you do it. The water going out forces the air in the empty bottle to go into the full bottle through the centre, creating a vortex.
Hooray! You’ve just made your very own bottle tornado.