What is wind?
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.
RICHARD: What is wind? Sounds a simple question doesn鈥檛 it? But how does a wind actually start? To find out I鈥檓 visiting a place said to have the worst weather in the world. This is Mount Washington in New Hampshire, USA. And it鈥檚 perfect for the experiment I鈥檝e got in mind.
TO CAMERA: Well, we are now at the summit. You鈥檙e going to have to trust me cos you can鈥檛 see much through there, but through the cloud, and the snow, and the howling winds, this is the top of Mount Washington. [INDICATING LONG TUBE] Now, you might have been wondering what this was all about when we set off. I know some of the crew were. Well, what I鈥檝e done in this device, hopefully, is I have caught some wind. There was nothing in it when we set off I just closed the valve - there is now wind in there.
I鈥檓 going to release it shortly, and what I鈥檓 hoping is that as the wind rushes out that I鈥檝e caught in there it鈥檒l move these little filaments here so that we can actually see it. This all seemed like such a good idea when we came up with it. Got one go at this鈥 Right - here we go. [RELEASES VALVE.] Did you hear that? And I saw it as well. That was wind - and it was, it鈥檚 the basis of wind anyway. Because when this was down at the bottom of the mountain the air pressure around and inside this tube was higher than it is up here at the top. So, I shut the valve, captured that higher pressure air in there came up here opened the valve and thehigh-pressure air rushes out to the low pressure. [HISS.]
NARRATION: The height of Mount Washington is enough to create a pressure difference. And pressure differences of various kinds are what create winds.
How to use wind to forecast the weather
TO CAMERA: Right, here鈥檚 how to amaze your friends. First, stand with the wind at your back. Then you鈥檙e looking for clouds.If those clouds are moving overhead, directly away from me, or directly towards you, or they鈥檙e stationary, then the weather is going to stay broadly the same.
If they鈥檙e moving from left to right, it鈥檚 going to get worse. If they鈥檙e moving from right to left, it鈥檚 going to improve.
NARRATION: So鈥 Right to left, better. Left to right, worse. Straight down the middle, stays the same. As long as you have your back to the wind.
TO CAMERA: Unless you鈥檙e in the Southern Hemisphere, in which case you reverse that bit. Brilliant, isn鈥檛 it?
Richard Hammond demonstrates how wind is created by differences in air pressure.
He begins by collecting a sample of air inside a sealed tube, transporting it to the top of Mount Washington. Mount Washington is said to have the worst weather in the world, with some of the highest wind speeds ever recorded: 231mph.
At the summit of the mountain 鈥 Richard explains that air taken at sea level has a higher pressure than at the top of the mountain. Wind is created when there is a pressure difference.
Teacher Notes
Key Stage 3
This short film could be useful in providing a simple explanation of how wind is formed, and could be used when introducing the concept of air pressure.
You could pause the clip halfway through and ask your students to predict what will happen when Richard releases the air collected. Were their predictions correct? Why did they make that prediction?
Key Stage 4
This short film could be useful when revising the concept of air pressure. Students could be asked to predict what will happen when Richard releases the air collected at sea level.
They could apply their knowledge of pressure changes and discuss what they think would happen in groups.
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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