A tornado in a bottle

What you need

• two plastic bottles
• two plastic bottle caps
• scissors or a small drill bit
• super glue
• hot melt gun or duct tape
• water

Procedure

1. Use the scissors or a small drill bit to make a hole in the middle of the two caps. The hole should be 5 mm in diameter. Then glue the two caps firmly together. You can stick them together with super glue or heat them over a burner and press them together. Then wrap the duct tape around the caps.

2. Fill one bottle with water. You can also add food colouring. Leave the other bottle empty. Screw the connected caps onto the bottle of water and screw on the empty bottle.

3. Turn the bottles so that the full one is at the top and spin the whole thing in a circular motion. It takes a little practice to create a tornado in a bottle. Right after turning the full bottle, it helps to squeeze it to get the tornado moving faster.

Explanation

When the bottles are still and in the upright position, the air pressure in the lower bottle in conjunction with the small through hole (the surface layer acts as a stopper) prevents the water from flowing out. However, if you set the water in motion by moving the bottles around and round, the surface layer in the through hole is disrupted when the vortex is formed and a tornado of air enters upwards through the centre and the water begins to flow downwards through the centre.

Tornado in nature

A tornado is a fast-spinning vortex that touches the Earth's surface at least once during its lifetime and is strong enough to cause considerable damage. It is capable of lifting an object weighing as much as 5 tonnes up into the air. It takes the form of a funnel, a trunk that descends from the clouds.  The wind in a tornado reaches speeds ranging from 50 to 100 m/s or more. Tornadoes occur in storms almost all over the world, with the American Midwest and South being the most well-known areas.

🔗 See more experiments with Mendel here.