Fun Friday - the Tornado

(Apologies I am posting the Fun Friday blog a day late due to broadband difficulties yesterday )

We all thought we had been visited by a small tornado here in Galway yesterday, a photo of a waterspout just off Salthill was the talk of the town.  Turns out it was just a hoax, but for any junior scientists that may be disappointed I thought I would share a great experiment with you explaining how to make your very own tornado in a bottle!  There are plenty of fun and interesting tornado facts too.


What is a Tornado?

photo credit: Niccolò Ubalducci Photographer via photopin cc

A tornado is a rapid swirling column of air that stretches from a cloud (usually a thunder cloud) to the earth below.

A tornado that forms over water is often referred to as a waterspout.

If the column of air does not touch the earth it is referred to as a funnel cloud.

How do Tornadoes form?


The formation of a tornado requires a combination of a number of specific weather features but usually tornadoes form when an area of warm, wet air meets and area of cool, dry air and alter the atmospheric conditions.  When this causes the warm wet air to rise and cool rapidly thunder clouds are formed.  Under the correct conditions of wind strength and speed the rising air starts to tilt and rotate and the tornado begins to form.

How fast is a tornado?


Most tornadoes have a wind speed of less that 160 km and hour (100 miles an hour), however, some extreme tornadoes can reach much greater speeds, up to 300 km an hour!

Did you know... the fastest recorded tornado was the Tri-State Tornado (Illinois, Missouri and Indiana) of 1925 had a forward speed of 117 km per hour (73 miles and hour)?


How are Tornadoes measure?


Tornadoes are detected using weather spotting and doppler radar.  Tornado warnings may be issues for certain areas by observing the formation of developing weather patterns while radar can be used for more accurate forecasting once thunderclouds have developed.

Image credit: Wiki Commons; a category F5 tornado in Manitoba, Canada, 2007.
It is not easy to determine Tornado strength and wind speed for two main reasons..

  1. as the exact location of a tornado is hard to predict it is very hard to have the required equipment in the right place at the right time;
  2. the force and strength of a tornado can destroy the equipment used for such analysis.

One of the devises used to measure wind speed within a tornado is called an anemometer. Doppler radar can also be used for this purpose.  When these measurements are successful, wind speed will be expressed against the Beaufort wind scale, ranging from 0 -12 in wind speed.

In 1971 Dr. Tetsuya Fijita developed a scale to rank Tornadoes, this scale ranges from 0 to 5 and is expressed as F0, F1, F2, F3, F4 and F5.  This ranking is retrospective, estimating wind speed and strength by examining the damage resulting from the Tornado.  This scale has been further refined in the US leading to the Enhanced Fijita Scale.

Do we get tornadoes in Ireland?


There are certain places around the world that are "tornado hot spots" such as many central states in the US, South Africa, Canada and Bangladesh.  However tornadoes can form almost anywhere and there are genuine cases of tornadoes in Ireland.  If we do get visited by a tornado it is usually small and brief.

Did you know...the earliest recorded tornadoes in Europe occurred in Rosdalla, near Kilbeggan, Co. Westmeath, on April 30th 1054?  

The only continent where tornadoes have not been recorded is the Antartic.

Did you know that the UK has the largest number of tornadoes per land mass?  Usually these tornadoes are small.


An experiment to try at home


Make a tornado in a bottle


You will need... two empty 2 Litre plastic bottles, an O-ring, strong duct tape, food colouring, glitter (optional). Alternatively use a tornado tube to replace the O-ring and duct tape.

What to do... Fill one 2 Litre bottle 2/3 full with water, add a few drops of food colouring and about a teaspoon of glitter, if using.  Place the O-ring on top of the bottle and tape into place with the duct tape, ensuring that you do not cover the whole.

Place the second (empty) bottle upside-down on top of the first one and tape securely into place.

If using the Tonrado tube you just twist the tube onto the first bottle 2/3 full with water and then upturn the second bottle and twist it securely into place into the other end of the tornado tube!

Once you are confident that the bottle is taped well enough to prevent any leakage you can turn the bottles upside-down so the one containing the coloured water is on top.  Turn the upper bottle in a circular motion about five times and then hold the bottles steady and see what happens.  You should a mini tornado forming in the bottle as the water drains.  if this does not work for you first time don't worry, it make take a few attempts to get the knack of turning the bottle correctly.


So what is happening?... When we turn the bottle we get the water moving in a vertical, circular motion, just like the air in a tornado.  Once we stop turning the bottle and hold it steady the momentum created causes the water to keep turning and form into a "twister" inside the bottle.  The food colouring and glitter or only present to make the tornado more visible.

Alternatives:


You can change this around a little by adding different things to the water in the bottle and compare how the tornado looks;  Some suggestions include adding grains of pepper, small pieces of coloured paper or a squeeze of washing up liquid.  You can also try the experiment by adding some coloured oil to the water.


Challenge your friends and family:


You can change this into a fun challenge for your friends and family and help them learn about air pressure while too.  Give your friend the bottles all set up and ask them how long they think it will take them to get the water from the top bottle to the lower bottle, without squeezing the bottle.  Let them have a go and time it.  You can then ask if anyone else thinks they can beat that time and give them a go.  Everyone should get about the same time.

Now it is your turn, upturn the bottle and start the tornado and time how long the bottle takes to empty now!  They should be impressed to find out you have beaten their time!

So what is happening?
The hole in the O-ring allows air to pass into the bottle, producing a funnel of air within the column of twisting water.  The movement of air from one bottle to the other equalizes air pressure and allows the water escape into the lower bottle much more quickly.


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