Inside a tornado
NARRATION: Wherever you live on the planet, weather shapes your world. Yet for most of us how it works is a mystery. So, I鈥檓 going to strip weather back to basics, uncovering it鈥檚 secrets in a series of brave, ambitious, and sometimes just plain unlikely experiments, to show you weather like you鈥檝e never seen it before.
Tornadoes are the most powerful winds on earth. They move far faster than a normal wind - not in a straight line, but in the speed that they can spin. And it鈥檚 that spin that does the damage.
TO CAMERA: Look at it this way. If I鈥檓 spinning this bucket around my head, it鈥檚 not how fast I鈥檓 walking towards you that dictates how hard it will hit you when I get there. Even if I walk really quickly, that speed is irrelevant. It鈥檚 how fast I鈥檓 spinning the bucket that matters, and what鈥檚 in it to add to the weight.
And that鈥檚 how it is with a tornado. Debris does most of the damage - that鈥檚 the weight in the bucket. The most destructive force in the tornado itself is its spin - its rotational speed - which is why it鈥檚 remarkable that鈥檚 the part of a tornado we know least about.
NARRATION: To try and put that right, I鈥檓 visiting the distinctly un-tornado-like landscape of Ontario in Canada and one remarkable building. [ALARM SOUNDS AIR RUSHES.]
TO CAMERA: I鈥檓 going to do something a person wouldn鈥檛 normally do. I鈥檓 going in! It鈥檚鈥 Oh! I鈥檓 in! This is it. I鈥檓 in the eye of it. And, all I can say is yes - this feels as amazing as I suspect it looks. I鈥檓 in a tornado - it鈥檚 the most astonishing feeling. It鈥檚 dizzying. The world is roaring past spinning round me but I鈥檓 still. This is massively scaled down of course. A real one would be maybe 100 times bigger, and the wind moving four, five times faster. But nevertheless, you get a sense of 鈥 the relentless terrifying power ofone of these things in the wild!
NARRATION: This is the Wind Engineering Energy and Environment Research Institute - or Wind EEE for short. And it鈥檚 the only place on the planet capable of duplicating the real-life dynamics of a tornado. It does it by using 106 giant fans hidden behind the walls and ceiling of the world鈥檚 first hexagonal wind tunnel. The whole structure cost $23 million. Which makes it all the more delicate asking it鈥檚 boss - Professor Horia Hangan - for a little favour鈥
RICHARD: Just while we鈥檙e here, I鈥檇 really like to just have a little look at velocities - sort of that way - in tornadoes. Can we have an, I鈥檓 not going to say - experiment a bit with it? Do you mind if we make a bit of a mess? Not a massive mess. There might be 鈥 We鈥檒l sweep up.
HORIA HANGAN: Mmm鈥
RICHARD: You won鈥檛 know we鈥檝e been here. Everything will be gone.
HORIA: That鈥檚 fine. We can do a little bit of a mess here, so we are prepared to catch some stuff that you throw into it.
RICHARD: Might happen. Thank you.
HORIA: You鈥檙e welcome.
NARRATION: Good for him - he鈥檚 trusting us with his $23 million baby.
TO CAMERA: Right - plan. I want to look more into velocity, see how fast the wind is moving and if I introduce these ping-pong balls into our tornado, I can measure the speed. I鈥檓 going to feed them to it.
NARRATION: We think of tornadoes as sucking up everything in their path. Turns out, it鈥檚 not that easy. I retreat to the control room, where the professor and I spend the next four hours trying to get something - anything - to actually fly inside the tornado. With no luck. Then, one of the scientists finds these pink foam squares, which might just be light enough to do the trick.
TO CAMERA: If we can get those foam squares trapped in the tornado, and we can get them lifted up and spun round without being spat out, then we might be able to time how long it takes one to do a full lap.
HORIA: I鈥檓 going to start the fans.
RICHARD: You see? There it is.
HORIA: Looking good.
RICHARD: Yeah. Yeah!
RICHARD: Normally it鈥檚 impossible to judge a tornado鈥檚 speed near the ground, because of all the debris and objects in the way. But here we have a real chance. Time to turn on the tracking technology. The computer follows individual squares one after another. So, it can create an average speed from the different trajectories. And it works - according to the computer it鈥檚 spinning at a shade over 22 mph. A real tornado could be ten times faster than that, but this is still the first time any tornado has been measured this near the ground. If we could find a way to do this in the wild, then we might change our understanding of tornadoes forever.
Richard Hammond explores the properties of a tornado that has been created in laboratory conditions.
He learns about how tornadoes cause damage 鈥 it's the speed of the spinning within the tornado, rather than the speed and direction of the whole tornado.
The main cause of damage in a tornado is from the debris carried by the phenomena. Richard visits a tornado wind tunnel at the WindEE Research Institute in order to demonstrate how the speed of rotation can be modelled within loose scientific conditions.
He considers the effects of tornadoes before demonstrating how the speed of a tornado alters through a cross-section, tackling the misconception that tornadoes 'suck up' everything in their path.
Teacher Notes
Key Stage 3
This short film provides discussion points around experiment design and measurement. How can modelling a tornado inside a laboratory help people living in the real world?
For example, it鈥檚 very difficult to measure the velocity of a tornado in the real world due to the debris being carried. Compare the speed of the lab tornado with the Beaufort Scale 鈥 what damage would be done? How could Richard have designed the experiment to be more effective with more accurate and reliable results?
You could stop the clip after the segment with the ping-pong balls and discuss how to make the experiment better - what material could be used? What properties would that material have?
Key Stage 4
This short film could be a good introduction or revision of the forces involved in a tornado such a Coriolis. Students can be asked how they would work out the velocity within a tornado 鈥 what data would they need?
Curriculum Notes
This short film could be used to teach geography and physics at KS3 and KS4 in England, Wales and Northern Ireland and National 5 in Scotland.
At GCSE it appears in AQA, OCR A, EDEXCEL, EDUQAS, WJEC and CCEA, in SQA at National 5.
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