Richard Hammond Investigates Temperature | Richard Hammond's: Wild Weather | Spark

whether one of the most astonishing forces on earth capable of both devastating power and spectacular beauty wherever you live on the planet whether shapes your world yet for most of us how it works is a mystery to really understand whether you have to get inside it so I'm going to strip weather back to basics science uncovering its secrets in a series of draining ambitious and sometimes just plain unlikely experiments to show you whether like you've never seen it all whether no matter how rare or how unusual can be broken down into three simple ingredients wind water and temperature with just those three things you can create pretty much any weather you want but the most important of the three is temperature in this program I'll discover how without we wouldn't have any weather at all all that's bothered us now how a dust storm in Africa can make rain right here and have it can produce snow as hard as concrete [Music] almost all our planets heat is provided by the Sun and we tend to think of the Sun as the source of all our best weather if you're looking to unlock the secrets of the weather the heat coming from up there is not as important as when it's coming from down there from the ground [Music] I know it sounds unlikely but it's all to do with the fact that the Sun heats the earth unevenly sand gets hotter than water tarmac gets hotter than sand concrete gets hotter than grass and these differences produce pockets of warm rising air called thermals which drive winds and create clouds but how can you see that effect for yourself well with a quarry five vehicles worth of kit and two specially built metal tables these tables are going to be our hot ground because they're dark in color they should soak up lots of heat from the hot Sun and to make sure they get hot enough we're going to give the Sun off to help with 14 gas canisters all connected up to 18 ipav burners we reckon with these we can get our table up to 200 degrees C maybe even higher and I'm hoping that's enough to show you and does to our weather to be perfectly clear my ambition here is not to actually make weather with this I'm not hoping for a little square cloud overhead the theories right it's just the scale is a bit small what I will be doing is creating that rising column of air that thermal which is part of the weather and it is something I will be able to show you once I've got it established so let's do just that turn on the gas fire up the burners and get those metal tables as hot as we feasibly can enabling me to fly some paper helicopters yeah I know but bear with me there is method English okay right going up time for my high-tech thermal indicators now normally a paper helicopter would just spin slowly to the floor but it doesn't it hovers why there you go there you go there you go [Music] you can see how we've created a thermal that mare and the helicopters that catch it are flying in that column of rising air [Music] [Music] the updraft is enough to hold the helicopters in place [Music] just as they do naturally with clouds rain drops and hailstones [Music] oh yeah but as the heat coming off the metal table increases the helicopters begin to climb [Music] until they're disappearing as a site which is how it should be a real thermal can reach 1500 meters and they have an important role to play in our weather we've all seen how puddles dry up on a hot day but where does that water go well those thermals take it up into the air until it gets high enough and cold enough that it condenses back into drops and forms a cloud but there's another result of this uneven heating of the earth it produces deserts and deserts play a very important role in what happens next to those clouds [Music] it's hard to imagine I know but right now I am surrounded by desert and not just any desert either probably the most famous desert of them all the Sahara [Music] and there it is that is Sahara and sand and it's not just on this car it's on all these cars and this bench pretty much everywhere in fact somehow it's managed to travel a huge distance all the way from Africa more than 2,000 miles away so how on earth did it get here well first you need a particularly Sun part part of the planet and then you need a dust storm dust storms are the way nature gets dust off the ground and into the air a big one can easily be a mile high and a hundred miles wide a vast moving wall of dirt but even the big ones only travel between 25 and 50 miles before they die out so how does the dust end up 2,000 miles away on the bonnet of a car in Bristol well believe it or not it bounces there let me try and show you what's going on imagine this tennis ball were a grain of sand drop it from waist height and it bounces up about two feet now imagine this ping-pong ball were a smaller particle of dust dropping from the same height and it bounces up about the same distance but if I drop them both together watch what happens then yeah the ping pong ball flies off what's happening actually is the ping pong ball is smaller and lighter all the kinetic energy the bounce in this ball has been transferred into it and away it goes obviously real dust comes in many more than just two different sizes which is why this is maybe a better analogy for different sizes of ball this time stacked loosely on this plastic spike in the center obviously real dust doesn't have a plastic spike connecting it but your alternative is you watch for 10 hours was I try and drop all four in a lie let's see what happens this time [Music] it's gone the small-bore live government it's just I'll show you again but I have to wait for it to re-enter the atmosphere I think seriously it's gone so that's the principle but can actual dust really do the same thing even with the power of a huge dust storm behind it to find out I'm going to the source of most of the world's dust not the Sahara but South Australia we're dr. Craig strong has offered to help me start a dust storm of my own what are you actually looking for well I'm looking Richard for the landscape that's going to produce dust and I think this stony plane is probably really good because you can see these rocks they're acting as a trap for dust so I think if we dig down we'll find that there's plenty of dust it's just that means it hasn't blown away yet because of the rocks I walk in all that dusting so when I see an area of rocks like this out here I assume all the dust has gone you think it's trapped underneath absolutely so if we have a look down here Richard once we get under there it's just dust gold look at this and see that just blowing away so there's lots and lots of fine material this is exactly what we want that's what Gus don't really Madoff the problem here is that the dust is trapped under these stones that's why you know it's here but it is trapped absolutely how do we get out the rocks are doing the job of protecting the soil so I reckon we probably should pick up the rocks and move them there flick away that's the first step Jeremy check it out the view that's right that's easy well I say me but actually I mean this channel Trevor who just happens to have the very tool for pushing aside all those stones it's not long before he's cleared an oblong area the size of a couple of football pitches and it has an immediate effect yeah dust devil that's amazing probably those swirling winds come through here all the time but because we've taken the stones away and uncovered the dust for it to be picked up we can suddenly see them but it's not what we're looking for we want to make something just that little bit bigger what dust Oh coming right up right away if you want here I would say does it do nicely do this in what is effectively the home of half of the world's dust over a trigger an international incident you get up tomorrow you sideboards covered in dust because I starred in this that's a lot of dust I knew that broke ins just to help the look I decided to lend a hand that's good innit [Music] our blokes live around here happy to come out all in the name of science [Music] this is a dull [Music] oh that's fun attacks man and it seems to be working in amongst all the cars in chaos the dust is starting to bounce [Music] individual grains are colliding against each other just like the rubber balls dead and notice that they're not just bouncing in the direction of the wind they're being propelled upward [Music] [Music] well there it is we've got the dust bouncing just like it does in a real dust storm but in a real dust storm it bounces much higher much higher than the storm itself can we do that here today there is only one way to find out Craig has brought in another dust expert to help professor Nigel tapper who specializes in measuring airborne dust with his assistance we should be able to see just how high we can get our dust to bounce it looks like this is something you're about to fire at your balloon what is it we've got a pump arrangement here that pumps at about two and a half liters per minute through this cyclone sampler that we can put underneath the balloon to sample dust at various levels that was a fly yeah quite an effect particularly tasty here dry start tie it onto the balloon string yep I'm gonna run it through here this is the tricky bit which way to roll oh yeah on the bottom to watch this go well I've got it now watch it's that way perfect you see you've done it before well no why would I have done this before okay wedging up we're winching not whinging napalm joke yeah I know I'll just Chuck Nigel plans to put three dust samplers under the balloon one three metres which was about the height of the cloud we created with the cars one at eight meters more than double that height and one at twenty meters because well that's how much stream we've got that extra vein at the top is carrying a miniature camera so we can keep a close eye on what's going on and to make sure we're doing our very best impression of a real dust storm we've wheeled in a couple of enormous fans to supply some extra wind so my job now is to try and keep the balloon which is suspended from the winch over there through this hook at the right height in the best place to catch the most dust kicked up by a dust storm and one important thing to bear in mind this all seemed very big I mean it's a very big balloon we're using big tools to make the dust but we're imitating the weather this whole experiment in fact is tiny but the principles are just the same and hopefully the fine particles will end up on top or me if this balloon goes much higher at this point add them on the smallest blow care why I've got this job don't know we'll be alright are we ready [Music] vehicle is churning the surface the patterns do the job of the wind [Music] [Music] put my goggles on that would be better [Music] sorry peasant contestable from him [Music] so now I just need to keep the balloon in the densest part of it [Music] basically if I can't see or breathe then I'm probably in the right spot the different pumps at different levels are sampling the air and the dust carried by at different heights actually the directly to the system on the top but there's only one way to know for sure check what's in those pumps luckily Nigel has a makeshift laboratory right on site we really interesting to crack these open and see what we've got we've got to be a little bit a little bit clean all right now we've got the insult out of the way time to see what we collected in the lowest pump and if it's not dust we've got a problem because that was slap bang in the middle of our homemade dust storm okay beautiful we were only sampling for a short time and there's a lot of it as you can see so let's move up and I like to 8 meters up into our homemade dust oh let's see that that's right let's have a look at the filter paper turn a little bit of smudging so we've actually got a bit of fine material at 8 meters okay now at 20 meters at 20 meters which was well out of the edges on out of dust there is any here this is the finer particles that have managed to bands themselves that will be on the top of our doom of dust up the right way there we go well look there is smudging it is there is a smudge so we did get a bit of material up there definitely some there so I think we can count that as a success we've got dust at least five times higher than our cloud so we must bear in mind when this experiment though to us it was quite big it's actually tiny in terms of the weather is in my mute so this upper level for us 20 metres that was outside of our plume of dust if that were scaled up to be whether to be a dust storm that could be thousands of feet if we were looking in a real dust storm making it up two to three thousand meters it's an amazing process a large dust storm can move 15 million tons of sand in a single goal many are so big that they can be seen from space and when that dust has bounced high enough it gets caught in global wind patterns which move it around the planet once in the clouds dust plays a crucial role in our weather because dust is central to the story of rain water vapor needs something to stick to if it's going to turn into raindrops and dust is perfect so down the dust comes and carried by the water drops out of the sky and onto your car so without the Sun beating down creating deserts and dust you might not get rain kind of ironic isn't it but there is one rare type of rain that doesn't need dust what it does need is cold it's a weather phenomenon unlike any other one that can take any of these objects [Music] and trap them like flies in amber encasing them in a hard plastic looking shell it's called freezing rain and as its name suggests it's completely dependent on temperature but it's not just the weather that needs to be below freezing the rainwater does and I'm gonna try and recreate it for you right here right now actually I'm probably in the best possible place to do that Montreal Quebec Canada because it happens more here than just about anywhere else in the world right oh yeah that's perfect really very cold which is what I want the air temperature here right now is about minus 10 degrees C but as long as it's somewhere near freezing the air temperature doesn't matter it's the temperature of these objects I need them to be really cold and they definitely are so I've got water that's below freezing but it's still in liquid form and I've got a hose let's see what happens when super cold water hits super cold object it's not complicated I've begun well it might not be complicated but it is effective the moment the spray hits the hydrant it turns instantly to ice fully formed blobs of ice that appear right in front of your eyes instead of dripping into icicles it solidifies immediately so how does it work we've already seen how raindrops need an impurity like dust to form but freezing rain is formed when a snowflake falls through a freaked layer of warm air on its way down now it's rain but rain without any dust inside it the temperature of the drop can go below freezing without turning to ice until it touches something cold to try and recreate that I'm spraying distilled water starting this I feel is good but it's gonna take a while I could be patient and wait or just tweak my approach a bit [Music] [Music] [Applause] bigger is better [Music] the water in the truck has been outside for days so normally it would be frozen too but fire trucks in Canada have a constantly revolving drum inside them that keeps the water moving a bit like a giant slushy drink dispenser this is strangely addictive I'm gonna have done a little bit there and now I just want to do everything more have a go certainly it gets the job done quick so let's see what we've got [Music] [Music] okay that completely encased in crystal clear ice and that's exactly where our one [Music] it's the clarity of the ice that makes freezing rain so unusual that and the fact that it completely surrounds any object it touches it's not just I see where the objects face the hose its I see everywhere in a perfect even coating leaving the objects rigid but unharmed [Music] it's gonna be shouting man that luckily freezing rain is fairly rare but it does hold the secret of how we get frost just like our fire hydrant and phonebox these leaves have cooled below freezing the differences frost grows without falling as a liquid first the ice crystals just magically appear literally out of thin air but when ice crystals grow in the air instead then something even more magical happens they become snow [Music] all snowflakes start off as an ice crystal a six-sided shape a bit like this [Music] but then temperature begins to play its part just a little extra moisture in the air and arms start to form at the corners a degree rise in temperature and the plate forms on one of those arms a two degree drop and tiny needles fall around them [Music] each of these my new changes stamp their identity onto the arts [Music] and they are so subtle the scientists aren't sure exactly why it happens what they do know is you end up with something like this a snowflake water in its most beautiful and complicated form except I made this one it's all my own work nothing at all to do with professional snow artist Simon cam over there is just repeat me well I did I did the fiddly bits I did that bit that's mine all my own work there really cool thing about all of this is that every one of these shapes is different I know it's a bit of a cliche no two snowflakes are the same but they're not I guess because of this infinite number of variations in temperature and humidity every snowflake really is unique not just in a handful of snow or in all the snow in this giant snowflake but all the snow that's ever fallen in the world or ever will fall that's because the conditions that create each snowflake are so unique that an individual shape can never be repeated [Music] but what's really amazing is that a snowflake never stops changing even after its landed temperature continues to transform it in the most surprising ways [Music] I'm interested to see exactly how so I thought I'd kill two birds with one stone provide a civic service for the good people of Davos by clearing this carpark sorry and conduct a little experiment but it's more of an illustration room [Music] yeah we're plowing first off I need to compress the snow as hard as I can manly work taking place last load robbing the real press this time come up I think that's about as slowly as I can get [Music] inevitably the hardness of snow is something scientists have considered and they've developed a scale associated with it five stages and it goes like this can you push a fist into it no next down four fingers this isn't as rough and ready as it sounds Astley the fist equates to 10 grams per square centimeter of pressure after the four fingers it's a single finger that's a hundred grams per square centimeter no if all of that fails they move on get serious a pen yeah so would end there but if that doesn't work the next scale is a knife I've got a knife I have actually just for the purposes of this dianna and then they see it for knife goes in and oh look it does haven't actually done that just because I happened to have a sword in my snowplow rack there is a reason this is all about the changing nature of snow the fact that it never seems to stop altering I've made it into this big man and made it as firm as I can but it's not finished there unless there's a sudden heatwave by tomorrow morning another significant change would have happened and I may have set the locals and interesting an unexpected challenge with my sword in the snow mustn't forget my pen overnight the snowflakes undergo a remarkable change all the arms and branches broke off as my snowplow crushed them up next to each other and now they begin to fuse together in a process scientists call sintering joining on to each other and the blade of the sword in one rigid structure this isn't freezing in fact the whole process works better when conditions are slightly warmer its restructuring the next morning we hid our cameras in a nearby shed thing and waited for the first curious locals to come past [Music] the sword is fixed as if it's set in concrete [Music] this isn't ice remember it's still snow snow that never stops changing all because of temperature when we think of temperature we tend to think of sunshine or lack of it but in fact the biggest influence that temperature has on weather is controlling the water vapor in our air evaporating it from the ground and the oceans freezing it into frost and snow or condensing it into fog I've come to one of the most predictably foggy places on the planet the Appalachian Mountains near Blacksburg Virginia almost every morning fog rolls up the Bluestone River and floods the valley [Music] this must be one of the off days which is why it's just as well I'm on this particular road because here they can make their own fog at the flick of a switch this is the Virginia smart road a two mile highway designed to test vehicle and traffic systems in different sorts of weather however we're going to use it to take a short diversion and answer a question I've often wondered about if fog is made of water then why isn't it clear why is fog white you know I'll never noticed how loud baggage London in Victorian time must have in Japanese luckily we're not planning on doing anything with sand we're doing it with night light is made up of lots of different wavelengths each a different color and we see those colors when objects absorb one wavelength and reflect another the light from this laser is scattering off the tiny particles of fog making each one visible but we are only projecting one color green and they're reflecting it the air around them hasn't reflected any wavelengths so it looks black project red and the droplets change color same thing with violet in fact they reflect every color and all the different ones together and they become white fog is just a cloud that's in contact with the ground so the reason fog looks white is the same reason clouds look white because they're scattering every color of light now you might be thinking hold on clouds aren't always white sometimes they're black well yes sometimes they appear to be black but that's mainly an optical illusion it's your brain exaggerating any differences there are to give you what it thinks is a more useful picture and I could demonstrate I've cut two holes in this piece of cardboard and if I put one hole over a white bit of cloud and one over what looks like a black bit in fact there's barely any difference and what tiny difference there is is caused by those minut water droplets fusing together to form raindrops the bigger drops of water make the cloud more dense which makes it harder for sunlight to pass through so we see dark patches that our brain exaggerates but sometimes there's no doubt that a cloud is black the sort of brooding storm cloud that serves is warning for one final type of weather the type that no show on weather should be without and it's a fitting conclusion because it requires all three of the key ingredients that we've looked at in this series temperature water and wind in equal measure when heat makes the grande intensely warm and the air is heavy with water vapor and strong winds mold the clouds you create a lightning storm this is one of the planet's most lightning prone regions Florida USA for most offers the most dramatic weather we're likely to encounter is thunder and lightning we've all heard thunder and seen lightning but here's the interesting thing it is actually possible to do the exact opposite to see thunder and hear lightning and I'm going to show you one way to hear lightning right now without even leaving on a car right first of all turn the radio on and tune it to the am frequency because this works best and then look for a point we haven't got a radio station yes tricky there's a lot of radio stations in the States but here we go there right between radio stations what we've got running static not surprisingly I know but some of that static is quite important to us listen for those quite distinct pops those are lightning strikes that might be happening some distance away but the huge electrical discharge is interfering the radio signal so we're listening to lightning happen and this system is so reliable that storm chasers actually use it to track down storms the louder the pops are the nearer the storm is let me just prove to you that this is electricity making this happen never could do this the static electricity have built up on the balloon effects the radio to see static it is interesting but no matter how effective all sometimes useful that method is it isn't the real and actual sound of lightning to get closer to hearing that I need to set something up because static isn't the true sound of lightning just as it isn't the real noise of a balloon this is a very low frequency detector and it can pick up lightning strikes from thousands of miles away too far away for any static to be an issue as the planet has more than a hundred lightning strikes a second I should have a fairly good chance of hearing a few between here and the other side of the globe what you're listening for particularly is whistles and that is the actual sound of a lightning bolt somewhere but if this is the real sound of lightning then what is thunder I've got another balloon now what happens next is no big surprise there's a big bang but what is surprising is where the noise comes from because it's not the material of the balloon if I stretch the rubber like so and pop it again there's no noise the noise is coming from the air as the balloon bursts the air inside it explodes out and that is a clue to how thunder works but to find out more I'll have to visit one of the few places in the world capable of creating full-blown thunder they do it by firing two hundred thousand amps of electrical current down this narrow copper wire exactly the same amount as in real lightning so this is it this is where it's all controlled yep so you'll need a pair of these like just going to be quite out is it to be any producing thunder okay so don't look directly at the arc because it's very bright right so I've come quite a long way to see something that I can't look at or listen pretty much good okay really well I suppose it is quite a lot of electricity we're playing with hit the kettle goes off these nuclear electricity to put in there capacitors okay um these on yep go have we started yeah right so now we see the voltage on the oh yeah so essentially this is gonna build up a colossal charge and then discharge it yep dad yeah I can hear what you're saying oh yeah in the top coaster you might want to put your hands over the defender just cower under the table you get their mind right it's it's 25 yep nearly there I guess they were ready so he can fire about on look if I won't listen then in fact was quite daggering ly loud yeah but really amazingly laughs yeah so was that thunder or was it just sort of the discharge of the electricity leaving and arriving no that was thunder but it didn't sound anything like thunder it was just like that yeah and that's because the lightning arc is only 20 centimetres long here in reality you've got a kilometer of an arc that's all producing sound and every little bit and it all arrives at you standing a couple of kilometers away at different times because a bolt of lightning is around a kilometer long some of it is further away from us another bit so parts of the San get to us quicker meaning that what we hear is multiple rumbles of that short sharp bang but it still doesn't tell us what thunder actually is luckily dan has a way to show us using slow-motion cameras and a line of lit candles it's the directors birthday another 56 candles to go we're getting there once again we return to the control room [Music] the candles are all blown out and if you watch carefully you can see that they're blown out one by one so what is going on well of course it's all to do with temperature a typical bolt of lightning is somewhere between two and five centimeters wide so something close to that these by the way are not the style reasons they're for protection because effectively I'm taking a shaft of sunlight as wide as this screen and focusing it down to something roughly the size of a bolt of lightning it is hot but it's nothing compared with lightning a typical bolt will reach 20 thousand degrees Celsius that's well over three times the temperature of the surface of the Sun itself thankfully it only lasts for about one ten thousandth of a second but that's still enough for something quite amazing to happen because lightning is so ferociously hot and explodes the air around causing it to rush out words like the air in my balloon what we see with the candles is that air moving away from the lightning bolt in a shockwave but just how powerful is this wave time for another experiment can thunder break these glass lightbulbs why agree light bulbs are delicate but are they delicate enough to be effective we think so we certainly think that the inner ring of light bulbs will go and not quite so sure about the outer ring one way to find out zapping yes [Music] they've been destroyed by the sheer force of the hot air exploding outwards well except that tough one at the back they hardly flinched but still pretty impressive I really want to see this one because I still can't believe it was strong enough that's a heck of a wave notice it's not the Lightning destroying the light bulbs the arc never even touches them it's the shock wave after the flash that does the damage notice also that the sound of thunder happens even later after the flash and after the bulbs have exploded and that is a lot of power isn't a lot of energy yeah and that's just from the Thunder the arc hasn't attached to the light bulb so that's just the shock wave that's broken the light bulbs which tells us how strong that shockwave can be but I want to see more what we've been looking at impressive though it is is the effect of thunder I want to look at the thunder itself with very specialized cameras we can actually attempt to capture that shockwave on screen not the effects but the actual shockwave itself that's absolutely brilliant that is the air exploding away from the hot lightening bottle at over 700 miles an hour I think we can that one a definite success so there you have it you can hear lightning and you can see thunder all because of the incredible temperature it gets to we've seen how temperature drives weather how heat gets water into the air and cold turns it into clouds how wolf creates winds that kanbans dust into raindrops and tiny fluctuations in temperature shaped snowflakes and frost and it all goes to show how our weather is endlessly fascinating a stunning display of magic and spectacle performed in front of us every single day [Music] even when conditions are wet and miserable there are amazing events going on just behind the scenes and though it may seem that only extreme weather is worthy of our attention [Music] the weather around us every day is equally full of wonder this is not freak weather it's our River and it's astonishing [Music]

Channel: Spark

Views: 733,082

Rating: 4.8118443 out of 5

Keywords: Spark, Science, Technology, Engineering, science documentary, science photography, science explained, science experiment

Id: DeYvP2A3QvU

Length: 57min 30sec (3450 seconds)

Published: Fri Mar 06 2020