Why is it so Windy Outside?

Flying away! Image Credit: Public Domain

By Naomi Dinmore (Intern for SMS)

It’s one of those days. Things are flying away, birds are loopier than usual and there’s no point even trying to have a conversation outside (because of the utter howling in your ears). Isn’t that annoying?

The wind.

It doesn’t care how annoying (or indeed fun) you find it – it’s just doing its job as a part of nature. We all know that the weather is weird and exciting and strange anyway, especially here in the UK, but what exactly makes it windy?

What causes the wind?

We have to start really big: with the sun.

As you probably know already, the sun heats up the earth, but because of the earth’s round shape, some areas get hotter than others. The equator is much hotter, because the sun’s rays hit it perpendicularly (perfectly head on), and the poles are much colder, because the sun’s rays hit it almost parallel (in the exact same direction).

The Sun’s rays hitting the Earth: Perpendicular and Parallel. Image credit: Public Domain

 

It’s like on a cold day, when it’s definitely much warmer to stand in front of the radiator than at the side!

In areas of warm air, the molecules (the tiny pockets of air) rise up, because they are lighter, and the cool air molecules sink lower because they are heavier. It’s like when you put oil on top of water it floats, because the oil is much lighter than the water.

You may have seen on the weather on TV those strange white squiggly lines. Those show the pressure of the air. (No, it’s not the kind of pressure you feel when you’re about to do a test or competition – it’s much more literal. Imagine an elephant was sitting on top of you. Painful, right? There, you’re under much more pressure than if, say, a mouse was sitting on top of you. That means that pressure is just a way of saying how much is pushing down on something.)

This means, that the heavier air molecules, the cold ones, give higher pressure on the earth’s surface than the warm molecules.

Have you heard of the saying: “What goes up, must come down”? Here it is no different. As the hot air rises, it becomes cooler as it is further away from the warm surface of the earth (like on an aeroplane when it shows you the freezing temperature outside – brrr!). This air, in turn, becomes heavier and rushes towards the earth’s surface to replace the hot, rising air molecules. It’s a continuous cycle, most notable when you get certain temperatures like today.

The heating and cooling of air molecules, causing the wind. Image credit: Public Domain

So, what makes the wind howl?

Have you ever tried blowing perpendicularly across the top of a glass coke bottle? (If not – give it a try – it’s a great party trick to impress your friends.) When you blow across it, the bottle resonates, meaning it vibrates a lot, which is what causes the sound.  That’s the same way the wind makes noise, but just on a much larger scale. That’s why, if you’ve ever lived in an old house with a working chimney, it is deafening on windy days – you can hardly hear yourself think!

Why then is the wind important?

Some of you may think the wind is annoying, and some of you may think it’s great! However, it can be very useful.

Did you know that the wind helps to pollinate the land? It carries important parts of plants far away for them to reproduce (I suppose this is bad news for hayfever sufferers – sorry!)

It is also responsible for the majority of the world’s weather (well, pressure is, anyway.) If we didn’t have any weather, we wouldn’t have important things like the water cycle, which is essential for life like us to exist.

Without the wind, humans would have not been able to get around at all until aeroplanes were invented. The wind has helped and still is helping sailing boats across the sea, which is important for trade, and even bringing nations together. Without the wind, we wouldn’t have Pirates of the Caribbean, and what a sad world that would be.

A pirate ship. Image credit: Public Domain

Wind can also be very useful for creating renewable energy, instead of using fossil fuels to power homes – like the wind turbines of Burbo Bank Extension in North Wales. Wind can really help save the planet, despite its noise!

 

Hold onto your hats! (And if you’re not wearing one, look out for flying hats coming your way.)

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Posted in Exploring Science, Physics