Head in the Clouds - Owain Wyn Evans, Gavin Pretor-Pinney, Amanda Maycock

Introduction

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Podcast Introduction

2:25Hello, I'm Brian Cox. I'm Robin Ince. And this is the Infinite Monkey Cage. Now, all of you, and I imagine there's been a few daydreamers here, when you stare out of the window at school, that's what they say. Concentrate! What are you doing staring out of the window? Well, for some people, it wasn't just daydreaming. It was practising to become a meteorologist or a cloud expert. Or an astronomer, I suppose. Or an astronomer. What time did you go to school? I'm from Oldham. It was dark 24 hours a day. I'm from Oldham, this guy, where it's always dark.

2:57Dark with industrial plumes. You've not bought your clogs again, have you? Because they made a right racket last time. I couldn't wear them standing on those volcanoes looking enigmatic, could I? Because the clicking would spoil the atmosphere. Oh, they're not made for going over cooled lava, are they? No. No. They made it wood. It's the worst possible thing to wear, to be honest, walking through lava, isn't it? Isn't it? There must be something... Well, paper, I suppose. Oh, no. Oh, of course, we only had paper shoes in Oldham.

3:28Yeah, whatever.

Cloud Discussion

3:29Anyway, today we're looking to the sky, but not as far as Brian likes to look. It's kind of parochial level of looking to the sky. We're going to go, well, really the level of clouds. The clouds that, of course, so often hindered your series Stargazing. Why were there always clouds there? Was it Dara O'Brien's head? Because I think because of the roundness of the head, they might have attracted clouds closer.

3:50Today we're asking, how do clouds help in maintaining... Maintaining? I can't say maintaining. I'll do it if you want. Here we go. You do it. You do it. Today we're asking, how do clouds help in maintaining a healthy atmosphere? What can clouds, which are so beautiful and so wonderful, and sometimes they shine with ice crystals, what can they teach us about the climate? Now you've got to do my line, doing me. To guide us through.

4:18That's better than having it. To guide us through. To guide us through, we're joined by a climate scientist. Don't worry, it's all right, the show's going to be OK. To guide us through, we're joined by a climate scientist, a cloud appreciator and a drummer. Oh, but so much more than a drummer. And they are. My name's Gavin Preeti-Pinney, I'm member number one and the founder of the Cloud Appreciation Society, which I started 20 years ago, and it brings people together from all around the world,

4:48120 countries. We've got members in, all united in the belief that, well, clouds aren't something to complain about. They're actually one of the most evocative and dynamic, and maybe you could say poetic, aspects of nature. And the most wonderful thing I've seen in a morning sky is a morning glory. Which, you'll be relieved. No! It is a cloud formation that forms in a remote part

5:19of northern Queensland, Australia. It's a cloud that glider pilots surf, just like surfers on an ocean wave. It travels across the Gulf of Carpentaria through the night and it arrives first thing in the morning on the Queensland coast. And I went there and I watched this cloud arrive. I rushed up into a plane with all the other gliders and watched them as they surfed up and down this cloud as the sunrise was breaking over the top of it. It was an absolute glorious and beautiful sight.

5:50Hello, I'm Amanda Maycock. I'm an atmospheric scientist and a professor from the University of Leeds. I used computer models to simulate the movement of the air within the Earth's atmosphere, including clouds and how it affects the Earth's climate. The most wonderful thing I saw in this morning's sky, there weren't many clouds around up in Leeds today, was actually Venus, which is visible at the moment. And Venus is another beautiful, cloudy planet, but a bit less hospitable than Earth

6:21because the clouds are made of sulfuric acid and they've contributed to a runaway greenhouse effect that means the surface temperature is more than 450 degrees Celsius. So that was the beautiful thing I saw this morning. Don't worry, you'll have those sulfuric acids before you know it. They're working really hard in the US. And also... LAUGHTER I'm Owyne Wyn Evans, used to be a weather presenter, now I am a TV and radio presenter and I'm also a drummer. I got the name The Drumming Weatherman when I played the drums to the BBC News music

6:52in lockdown and it went viral and then I went on to play the drums for 24 hours for a Children in Need drum-a-thon, whilst every so often also doing the weather. LAUGHTER And my husband was thrilled to have the drum kit out of the house for 24 hours and I was thrilled to throw the drum kit into a skip after the drum-a-thon. And the most wonderful thing that I've seen in the morning sky is a gigantic Peppa Pig balloon.

7:22Stay with me on this one. I live in Penarth, which is near the water in South Wales. And me and Aaron were going for a walk one morning and saw this kind of orb over the water. I thought, Aaron, what's that? Aaron, that looks like Peppa Pig. Or was it Daddy Pig, actually? As the balloon approached, it was indeed Peppa Pig. And it was drifting up the coast towards Swansea. Stranger things have drifted up the coast towards Swansea. And it turned out to be a child's balloon, which was somehow kind of amplified and expanded

7:55by the view across the sea. And Peppa Pig drifted towards us and off she went. Last seen off the coast of Barrie. As I think a lot of hopes and dreams have. So there we go. And this is our panel.

Guest Introduction

8:17Gavin, we should start with you. Why did you feel a cloud appreciation society was so important? It's because people do like to complain about them a bit. You don't need, like, a sort of kitten appreciation society because everyone loves them. You need something that's a society that has a kind of mission to shift people's perspective about the sky. At least that's what I felt. So it's really, I just felt someone needed to stand up for clouds, basically. Let's get this out of the way. What's your favourite formation? It's got to be a Pilius.

8:48Fair enough. That's a very strong answer. Amanda, we... To move back to the science. What, that's not science? No. Move back to the science. We had a man talking about a Peppa Pig balloon. You've got to bring them gently back to the science. I'm just saying, what's your favourite cloud? I didn't say favourite cloud. I said favourite formation, Brian. Is there a technical difference between that? Have I made a terrible mistake? A formation is just a general term.

9:19Because, I mean, basically, they're all clouds. They're these random appearances in the sky. But humans are amazing at spotting patterns. And so when we started to classify clouds in a scientific way, 1802 around then, and it was actually an Englishman called Luke Howard, a Quaker from Tottenham, he was spotting patterns and he started to give them Latin names. So he came up with the Cumulus and Cirrus and Stratus. And these names just basically say what the clouds look like.

9:52And you say it in Latin, sounds fancy, makes it sound scientific. See, Brian, you've put too much effort in learning physics.

9:59Amanda, how do clouds, at the most basic level, how do clouds form? So a cloud forms when a parcel of air becomes saturated and some of the moisture that it contains condenses. So where does that come from, the moisture in the air? Well, if you imagine standing and drawing a sort of square around your feet that was sort of one metre squared and you weighed all of the water above your head, there's on average about 25 kilograms of water all the way up to the top of the atmosphere, which doesn't sound like a lot, certainly a lot less than the rest of the mass of the air,

10:31but it is enough to form these clouds. So basically, the evaporation mainly comes from over the oceans. We've got the vast oceans that provide that source. And the sun heats the surface of the earth. The air warms up. Warm air rises. It moves up through the atmosphere. And as it does so, it cools and it expands. And it's that expansion and cooling that can cause the air to become saturated. And that's the point at which the cloud droplets can begin to form. But they don't just form by themselves. They need something to cling on to, as it were. And they tend to form around little things we can't see,

11:01specks in the air. They might be bits of dust, bits of pollen, fungal spores from trees. And the water molecules condense around those little particles and start to grow a droplet. And then where does the structure come from? Because we've heard that there are... How many... Is there a number for how many different types of classified cloud formations? Yeah, well, there are 10 basic type. The genera, the main types. And those are the ones you'll have heard of at school. Cumulus, cirustratus, cumulonimbus.

11:33The superstar, you know, the storm cloud that produces thunder and lightning and hail. But then there are lots of these additional ones, which are sometimes just a feature that looks just like a curl, like a tiny breaking wave, which would be called a fluctus cloud feature. There's a whole bunch of them. I think there's about... When you combine them all, it's probably about 80, something like that. And one of them actually came from the Cloud Appreciation Society. Oh, yeah. Yeah, one of the official types. So what is giving the clouds

12:04these different characteristics, broadly speaking? So there's two main sort of types of particle that we can find within clouds. There's liquid water droplets, and then there are ice crystals. And so a lot of the appearance and the differences in appearance come from how much liquid water they contain or how much ice crystals they contain. So the high-altitude ice clouds, where it's very cold, they have this kind of wispy appearance. They get sort of stretched out by the winds. So the winds are obviously blowing the clouds around. You can often see that on a windy day. You'll see them being blown along.

12:35The lower-altitude clouds, which are made from liquid water, the sort of fluffy, cumulus-type clouds, they're sort of formed because of the liquid water within them. So, Owen, what about for you? I know technically you'd be called a weather forecaster, but you weren't actually forecasting the weather. Yeah, that's right. Yeah. I came from a background of journalism. When I joined BBC Weather, the Met Office were providing the sort of data, if you like. So I was trained up by them and then later studied through the Open University,

13:06meteorology through a couple of modules, just because I think we love the weather here in the UK. It's the first point of kind of conversation for a lot of people. You know, if you don't know what to say, oh, it's lovely outside. Oh, it's terrible, isn't it? Not always that camp, by the way. It's terrible weather. But I think that, for me, the clouds are the things that a lot of people, you know, it's that thing that you can see. And I remember when I was doing the weather in lockdown, there was nothing to talk about

13:37because people weren't really going out. So the producers would give me three minutes to fill on the weather. I'm like, Hans, like, everyone's inside. But people would then start to see, like you were saying earlier, Gavin, about, you know, the clouds, you start to see shapes or faces. And I think that's what's amazing about clouds. It almost gives people a little bit of creativity, especially cumulus clouds, the fluffy cotton wool ones. What about, Gavin was saying about that there's a negative attitude towards clouds. I imagine when you were mainly doing the kind of,

14:09you know, the presenting of the weather, that you would get letters of complaint as if you yourself had created the weather. I mean, did you get that? Or I still do. I haven't done the weather for three years. And people say, oh, didn't forecast this, did you? So I went, hon, if I forecast this three years ago, I'd be monetising this skill somehow. It would happen a lot when we get, we would get bad weather as well. You know, if there were really bad storms and we'd get weather warnings, the yellow warning is the lowest, then it goes up to amber warning, which is my drag name as well.

14:43I do think weather presenters are a bit too apologetic. They sort of seem to feel that. Yeah. And they feel a bit guilty when they say, you know, there's going to be a lot of cloud around. And in an apologetic tone, I would like to hear a bit more detail about what cloud is going to be around. I'd like to know how the formations are going to be changing through the afternoon, what sort of shapes we're going to be seeing. I would like some more detail and a bit more positivity.

15:13I love that. I'd love that. We could do like a kind of a, what shapes will we see today in the clouds? Like a little bat, maybe. Did you used to send to, because they only used to have one shape of magnet for the cloud, didn't they? Whatever, whether it was a stormy cloud, whatever. It was sort of a bit of a sad day when they stopped using those magnets. But I mean, that is the cumulus cloud, the one that's in the cartoon. And it's like the sort of generic cloud, the cumulus. If you close your eyes and think of a cloud, it's one of these puffy white cumuluses that form on a sunny day.

15:44They feel the most solid. The word cloud comes from the old English word clude, which means a rock or a boulder. It's wherever we get the clod of earth, that term from. These feel like solid things, cumulus clouds. Do you know what I mean? And that's why I think they're kind of iconic for us. They have very, very distinctive shapes. And the edge of them is very well-defined, which seems counterintuitive. It's just this phenomena where water is condensing. So why do they have such a well-defined shape?

16:15So it's often because there's a sort of barrier of the air to be mixed from within the cloud to the surrounding cloud. So there's differences in temperature, differences in density between different air masses that are nearby each other. So that's what provides this kind of rather crisp-looking shape often. The base of the cloud will be where the kind of layer of the atmosphere starts to become saturated. I mentioned before the saturation is a sort of necessary condition. So again, that's something that will have a sort of well-defined base to it. And then at the top of the cloud,

16:45you'll move into drier air, warmer air above. But they're not sort of stationary things. What's actually happening in reality is that there's constant evaporation and condensation occurring at the base of the cloud. So the base of the cloud, the little droplets will be continuously evaporating. And then at the top of the cloud, they'll be condensing and reforming. So they're very sort of dynamic structures. So is that, because I sometimes, I do find it fascinating when you're looking out on a day where the wind is moving a cloud and you look at that cloud and you think it has remained in that shape.

17:15And yet, so actually within what appears to be that kind of, you know, the stationary nature of the shape itself, there is still all manner of movement going on there. Yeah, absolutely. There's a lot of motion that's happening within the clouds. In fact, that's one of the reasons why a cloud doesn't just fall out of the sky. You know, so a typical cumulus cloud, the ones we're talking about, might weigh somewhere between about 250 or 400 tons, something like a sort of typical 747 aircraft, something like that. There's a lovely gasp over there. People have got slightly more scared of clouds than they used to be. What if they fall?

17:46What if they fall? Chicken lick it? How big would that be? So a 400 tonne cumulus cloud. Yeah. What dimensions? So that would be of the order of a sort of cubic kilometre or something like that, one and a half kilometres cubic. That's a sort of typical size of a cumulus cloud. But, you know, of course, the gravity isn't acting on the cloud as a whole. It's acting on the individual tiny little droplets, which are of the order of a few thousandths of a millimetre across within the cloud. And so actually they only fall very, very slowly, perhaps, you know, a centimetre per second or something like that. And you actually have motion within the cloud,

18:16upward motion, which sort of basically sustains the altitude of those droplets. So they don't just drop out and fall down. They collide and coalesce with each other. They join up and become bigger droplets. And eventually, once they're heavy enough, they can actually fall out and become precipitation. This is the magic of clouds comes from the special nature of water that's naturally found in the three states of solid, liquid and gas. And that is really the secret of this kind of poetic

18:50and beautiful quality of clouds because they can appear and disappear at will because one of those states, the gas one, is invisible. And so we're at the triple point of these three states on Earth in the atmosphere of Earth. And so the clouds are revealing the changes, revealing the invisible movements of the air. These movements of the winds are happening the whole time. We only see them when they just nudge that water to shift state from the gas form we can't see

19:23to the liquid or the solid. That's a very beautiful thought, actually, is that they make the atmosphere visible. They're the face of the atmosphere. They're expressions on the face of the atmosphere. And so they can reveal the moods, the shifting, ever-shifting moods of the atmosphere. And we just intrinsically know how to read those moods. Ask a child when they see a cloud that is dark with a base that's low, and they know what's going to happen. They know that that's very likely to produce rain.

19:54You know, we've always known that. Right back to, I imagine, you know, when we were living in caves. Now we know the science of it. We know why. But they've always been this shifting expression on the atmosphere that, you know, I think we need to be more in tune with. I think it is good for the mental health and your well-being to be engaged with the sky, personally. What's the physics of that? So why are rain clouds dark? First of all, I mean, clouds look white, most of them. Liquid clouds look white because they're scattering the incoming radiation

20:25that's coming from the sun. And they scatter that radiation quite equally across different wavelengths of light. And that's why they look white. Often if you see a kind of grey cloud, it's sometimes a shadowing effect. So it's kind of the cloud's own shadow. So if it's a very large kind of low cloud, as you said, it's basically kind of shadowing and you can't see that scattering effect as well. How bright they look is sort of dependent on how they're made. So if you have lots of small little droplets within the cloud, then it is very good at scattering that light. It'll look very bright and very white.

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24:49One of the things that I love about clouds as well, you know, you mentioned there about how they appear white because they scatter the wavelengths of colour, but really scattering, which is what makes the sky blue because, you know, the sky isn't physically blue because at night time you can see through it up to the stars, right? And then in the morning when the sun is lower in the sky and the light is sort of grazing the atmosphere of the earth, those wavelengths

25:20are scattered again and you get more of the reds coming through because the red wavelength is kind of... Could we describe it a bit like a wibbly-wobbly wave? Is that right? Just a wave. Has that ever been said before? Just a wave. Just a wave, Brian, yeah. I didn't need to unnecessarily add wibbly-wobbly then. There's no un-wibbly-wobbly wave.

25:39To be fair, I think Owen was saying that this one was wibbly-er and wobbly-er and I think the wibbly-er wobbly-ness of this... Does he mean the amplitude or the frequency? No, I mean the wibbly-wobbly-ness. I think it's a longer wave, yeah. It's a longer wave. There we go. So it is more wibbly and less wobbly? Well, yes. Is it more wobbly and less wobbly? Oh, I can't remember. Brian, I know you've got a question for Owen because as usual last Tuesday you were with Gloria Estefan and the Miami Sound Machine and so...

26:10I was on the radio and it was Gloria Estefan and Bob Mortimer.

26:16Just duetting as usual. Yeah, and Bob Mortimer said, I have a question, and I said, what is it? And he said, you know, if you get a crisp packet and you open it and you eat all the crisps on an aeroplane and then open the aeroplane window and drop the crisp packet and it falls onto a cloud, will it sit there on the top of the cloud? That was his physics question. Can I just though mention, by the way, if you are an aeroplane, please don't open the window. No, no. It's just that we won't get letters. If you're an assessor, you'll be all right. Yeah, so...

26:46But I had to think for a moment. That's quite a nice question. So what was your answer then? Let's find out if Brian's answer is right and then I'll cover it to you, I want it. OK. I mean, they look so crisp, especially when you're in a plane and when the cumulus clouds are below you, but you have that kind of boundary in between what's cloud and not. It feels solid, doesn't it? Yeah, it looks solid. Solid. But then when you fly through those, you see it's just like, you know, flying through a cloud of smoke or like, you know, Friday night in my house when I've got the dry ice on. So I think the...

27:18Which the cat despises. I love that. The dry ice. Is that what it is? Like, put the dry ice on. I think it would fall through it. Yeah. I came to the conclusion that it would fall through. But it's a good physics question. Yeah. Yeah. The layer right at the top of the cloud is often quite turbulent because the clouds emit radiation. And so that can actually drive motions along the tops of the clouds. So I actually think it would probably get transported around

27:49by the air currents rather than being held up by the water droplets of the cloud. I think the actual turbulent motion, this sort of mixing effect at the top of the clouds because the clouds are emitting radiation out towards space would probably hold it up. Are you saying it would move in a wibbly-wobbly fashion? A wibbly-wobbly fashion. He thought he was being... I think he just thought he was being Bob Morton. But it's actually a really good physics question, isn't it? Because as you said, I didn't think of that actually, the radiation back out again. Yeah. Is that one of the reasons you feel turbulence

28:20when you enter clouds in an aircraft? Yeah, well, that's exactly what you're experiencing. All of those upward motions I described before that are happening, all of the local currents that are happening within the cloud is basically what causes that turbulence for the aircraft. The top of the cloud in particular because you've basically got a body which is emitting radiation, emitting thermal radiation, and that's dependent on the temperature at the top of the cloud, basically. So how cold the top of the cloud is determines how much energy it's going to emit out. Is it always hotter at a higher temperature than the air,

28:51the clear air above it? It depends on if it's an unstable atmosphere because in a stable atmosphere, a thermal might rise from the ground and come back down because it's not warmer than the surrounding atmosphere and you don't have clouds forming or storms developing. But in an unstable atmosphere as we describe it, the air gets more rapidly cold as you go up and therefore if you lift some air from near the ground where it's warm, it comes up, some droplets begin to form

29:21as it cools and remember every time a tiny droplet forms, a little bit of heat is released, the latent heat as it changes state and those all add up even though it's a tiny amount from each tiny droplet and this is like fuel to keep the buoyancy in an unstable atmosphere so the droplets form, it gets more buoyant, more droplets form, it gets more buoyant and you get building, building, building to this enormous cathedral of clouds that is the cumulonimbus storm cloud and within that

29:51these currents, vertical currents are rising rapidly in some areas, precipitation's falling fast in other areas and sometimes hailstones develop because these particles are going round and round and building up in layers of ice so Bob Mortimer's crisp packet could have ended up in the middle of a hailstone. It can be one of those very famous physics examples that all undergraduates learn in atmospheric physics, isn't it? Mortimer's crisp packet, that was the infinite monkey cage,

30:24you know? But just to pick up on that point because it's an interesting bit of physics, the fact that water droplets forming release energy. Could you just, maybe Amanda, just speak about that? Yeah, so going back to Gavin's triple point for water, so any time that water changes phase, so whether it goes from a gas to a liquid or from a liquid to a solid, in that direction it's, yeah, basically releasing a little bit of energy which is to do with the organisation of the water molecules basically within the structure.

30:55So once it condenses and it turns to a liquid, that little bit of energy gets released and as Gavin said that contributes to a heating in the atmosphere, it's basically this latent heating effect of the clouds as they're forming. And you get the opposite as well, so you could have ice crystals up at the top of one of these cumulonimbus clouds, they spread out in an anvil, this enormous plume of ice crystals, spreads out hundreds and hundreds of miles and in one area those ice crystals can melt and therefore change state in the other way.

31:25That makes the air cool a bit and you can get these sinking pockets that appear as mama clouds on the underside, these pouches of cloud on the underside of one of these cumulonimbus anvil plumes and they look really distinctive, these pouches of clouds and they're the result of the cooling, most likely, it's not totally understood, most likely the result of the cooling that happens with the shift in state the other way. We've all seen those, haven't we, those anvil clouds.

31:56Why are they so flat on the top of the cloud? So going back to what Gavin talked about with the stability of the atmosphere, so particularly in the tropics, we find a lot of these deep cumulonimbus clouds over the warm tropical oceans, there's a huge amount of fuel and moisture which allows these clouds to get up to altitudes of 18 or 19 kilometres, you know, this is sort of almost twice the height of cruise altitudes of typical aircraft, so these are really tall clouds and what happens is you hit a sort of boundary, we call it the tropopause, it's basically the transition between the lower part

32:27of the atmosphere where all of our weather happens and the clouds form and the layer above it which is called the stratosphere and it's called stratosphere because it's a stratified layer, it's a stable layer and so the clouds basically get up to this, it's almost like a lid, they can't move above that because the air above is stable and so they can only spread out and that's why you get these anvil clouds because they then just spread sideways because they can't travel further upwards anymore. And if you see the photographs from the space station where one of the astronauts takes a photo down onto cumulonimbus clouds, it's like there's this,

32:57it's like they've formed underneath a piece of glass with this temperature profile, this temperature inversion, we call it because it's the opposite of the normal getting colder as you go up, it starts to get warmer at the top of the troposphere and that's this invisible lid and the cloud you can just see spread out and it just can't go up and it wants to go up higher but it can't go up any higher because it suddenly gets stable there. This is another incredible thing about clouds is how you get so many different kind of shapes and reasons as why things look

33:29a certain way or are a certain way and they've intrigued people forever and I suppose it's only fairly recently that we as people have kind of fully been able to understand what these things are and why they're doing those things. I was going to ask