society, The Cloud Appreciation Society. And, no, it's nothing to do with the virtual cloud.

It's about the real ones up in the sky. It's for people who like clouds, people who dislike

blue-sky thinking. And we've got members in 94 countries around

the world. They're all united in the belief that we shouldn't just think of clouds as

things that get in the way of the sun. We shouldn't just think of them, shouldn't moan

about someone having a cloud hanging over them or a cloud on the horizon, because they're

what bring variety, beauty, drama to our skies. When was the last time that you sat back and

just watched a cloud? Just watched the way it builds in brilliant white, cauliflower

mounds? Was it when you were a kid? Before time was money? When your only deadline was

bedtime? They're so omnipresent, aren't they, so everyday

that it's easy to forget they're even there. It's easy to miss that in a way, clouds are

the most dynamic and evocative of nature's displays.

So for the next 15 minutes, we're going to forget about blue-sky thinking, and we're

going to see what happens when you open your eyes to the formations in this ocean of air

above us, when you pay attention to the things that other people miss.

So let's start with this cloud here. Does anybody in the audience know what type of

cloud this is? Are there any pilots in the audience?

It's a cumulus cloud, absolutely right. So this is the fair-weather cloud, forms on a

sunny day, borne up on invisible thermals of air rising off the sun-warmed ground. It's

the Simpson's cloud, all right? It's the generic one. You close your eyes, think of a cloud,

this is the one that comes to mind. And with its crisp, well-defined edges, it's also the

best type of cloud for finding shapes in. So it's usually a cumulus that you're looking

up at when you glance up and you go, wait a second, it's a goldfish.

[ Laughter ] It's usually cumulus there on the other side

of the river when you go, it kind of looks like a giant taking a stroll.

They're like nature's version of those ink blot images, aren't they? You know, like you

say, like shrinks used to show their patients. "What would it mean, Dan, if you look up and

you see up above the shopping mall there's the abominable snowman with a gun going to

rob a bank? What would that mean?" [ Laughter ]

>>> Probably to do with your mother. >>Gavin Pretor-Pinney: Probably to do with

your mother. Exactly. Usually is, isn't it? They're the natural stimulants, aren't they?

And who here hasn't at one time or another sat back and looked for shapes in the clouds?

But perhaps you don't do it so much now that you're adults. Perhaps it feels a bit frivolous

to -- a bit aimless, a bit frivolous to look up and go, wait a second, it's an angel with

a camcorder. [ Laughter ]

Perhaps it's -- feels a bit kind of, well, whatever when you go over and mention to your

neighbors that there's an Ostrich pecking on their roof.

It may be aimless, but that doesn't mean it's pointless. Because when you have your head

in the clouds like this, when your brain is in coasting mode, that's a chance, that's

a space for your subconscious to speak. And that's when you give yourself the space to

make connections, you know, make novel connections, come up with new ideas.

So, those cumulus clouds are nature's invitation to daydream. But those same clouds, under

certain circumstances, when the atmosphere is unstable, can build and grow up in the

sky. They can grow taller and taller, rising eventually to 8, 10, 12 miles up into the

sky. This is when they start to spread out at the

top, in enormous anvils covering over hundreds of square miles. It's where it's become the

cumulonimbus storm clouds. They're the king of clouds. These majestic beasts of the atmosphere

are what produce thunder and lightning and hail, and when they get together, they can

combine into enormous and destructive storm systems.

The cumulonimbus is the embodiment of the power that drives our atmosphere. And the

way it develops out of those innocent little cumulus clouds is an indication of the fact

that clouds are forever in flux, forever changing, metamorphosing from one form to another.

High clouds, like these Cirrus, are composed entirely of ice crystals. And unlike those

low clouds, those cumulus, they're composed of water droplets. So these are ice crystals.

And the way these ice crystals form through the sky is what gives this cloud its distinctive

wavy streaks. The Latin name for them means a lock of hair.

So as those minusculized crystals tumble from the upper reaches of the atmospheres they're

swept along in the high winds. 200, 300 miles an hour. And it gives them these very beautiful,

I think, wavy appearances. I think it's one of the most beautiful of the common clouds.

And these are common clouds. These and the cumulus before and the cumulonimbus are three

of the common types of clouds. There are 10 main types. But what about the rarer ones?

Because there are many more exotic and unusual forms.

For instance, the lenticularus cloud, which looks a little bit like this. There we are.

Lenticularus cloud. It's named after the Latin for a lentil. So this forms in stable air

in the region of mountains, and as the air rises to pass over the mountain, it can, in

certain circumstances, take a rising and dipping path in the lee of the peak with one of these

UFO-shaped clouds at the crest of the wave. It's a standing wave of air. So the air and

the droplets are all rushing through, but the position of the cloud remains fixed in

the sky relative to the mountain. And then there are mamma clouds. So these

come from the Latin for udders. And these pouches hang from the underside of the cloud

layer. The larger ones, the more dramatic ones form on the underside of the anvil of

a storm cloud. The exact mechanism for these clouds to form is still not clear to us.

But one of the rarest types of cloud is this one, the Kelvin-Helmholtz wave cloud. It looks

like a succession of waves with the tops curling over like ocean breakers. And this is caused

by shearing wind, so the wind above the cloud layer and the wind below the cloud layer differ

significantly, and in between you get this undulation where the cloud is. And if the

difference between those two speeds is just right, then the tops of those undulations

curl over in beautiful vortices. Now, all those clouds form within the lower

part of our atmosphere. All right? In the part called the troposphere but there's one

type of cloud that forms higher than these, much higher and it can only be seen at night.

The noctilucent cloud. It's 50 miles up in the atmosphere, so it's not in the stratosphere

which is above the troposphere. It's in the mesosphere, the part above that, which is

an incredibly cold and incredibly dry part of our atmosphere. And they get the name noctilucent

because being so high up, when the sun has gone down over the horizon, the sky has become

dark, these still catch the light. Noctilucent means light shining in Latin. They still catch

the light and they have these beautiful, eerie, rippled, sort of mysterious appearance to

them. Which is kind of appropriate because they are mysterious. We don't understand how

the water that forms the ice in these clouds gets up into the incredibly dry part of the

atmosphere. Nor do we understand since the end of the 19th century when they were first

observed, these clouds seem to be spotted more and more frequently.

A few years ago, somebody sent us from the states, in fact, from Iowa, they sent us a

photograph of a cloud that looked a little bit like this; all right? Looks like kind

of very turbulent sea. Very, very rough turbulent sea, maybe as if you're looking up from below.

And when people send them into the Cloud Appreciation Society, we put them up on the gallery and

we kind of nerdily decide what type of cloud it is and categorize it, as you do, and I

wasn't quite sure what to call these clouds because there is a name for wavy clouds, undulatus,

wave clouds, but these seemed like undulatus turned up to 11. They weren't your normal

undulatus cloud. Now we then got one -- another one got sent

in about a year later. In fact, every once in a while they would appear, and each time

I would go there's another one of those sort of weird nameless clouds. Until one day I

thought, wait a second. Maybe if they don't have a name, maybe these clouds need a name.

Maybe these clouds sent in for our network from all around the world should have a classification

of their own. And I thought how do you go about that? Well, you've got to come up with

a Latin name, haven't you? And I thought, well, I called up my cousin,

Phillip. He's a Latin teacher. And I said, "Phillip, what's a good Latin name could I

use for when the sea is rough or turbulent?" And Phillip said, "Glacialis hiemps aquilonibus

asperat undas." [ Laughter ]

I said it's a bit long. He said no, no, no. That is a term that translates -- that's a

quotation by Virgil, the Roman poet, and it means the waves were roughened by the icy

winter's northern gales, and the word you want in there is asperat. The verb aspero.

It means to be roughened. So asperatus would be the term you'd use for that, roughened.

So I thought great. Asperatus. That's what I'm calling it. But how do you go about making

a cloud official? Cloud classification official? I know you've all asked yourselves that question

at one time or another. [ Laughter ]

Well, I took it to the Royal Meteorological Society in the U.K., and I said, "What about

this? It's a new cloud type." And they looked at it and said, "Yeah, it's distinctive. You

might have a case, but you need to find out more about it."

So I took it to the University of Redding, and they said -- they looked into it, looked

into the way the cloud formed, stuff like that, and they said, "You may have a case

for this being a new classification." But it didn't matter what either of those

lots said, because the only people who matter when it comes to the official classification

of clouds is the World Meteorological Organization, U.N. organization based in Geneva. They publish

the International Cloud Atlas, which is no page turner --

[ Laughter ] -- but it is the final word in cloud classification.

So if you want your cloud to be official, it's got to get into the International Cloud

Atlas. All right? The only problem is -- Well, it's been first published in 1896 and they've

had versions every now and then since then. The problem is the U.N. don't do anything

in a hurry, as we all know, and they had no plans to do a new edition of the International

Cloud Atlas. They'd only just done one in 1974.

[ Laughter ] So I wasn't holding my breath. But I was very

pleased to hear just last week that perhaps as a result of being hounded by journalists

who kind of liked this story, you know, weird guy, wants to name a cloud, viral story handed

to them, they decided they are going to do a new edition of the International Cloud Atlas.

[ Applause ] They're going to put it -- They got their

experts to look into whether there should be any changes or additions to it, and they

have concluded that they think asperatus should be a new official classification. The first

new cloud type since 1951. [ Cheers and Applause ]

People often ask me where in the world is the best place to watch clouds; all right?

And one place has to be this, the Salar de Uyuni, which is in Bolivia. Southwest of Bolivia.

It's a very large salt flat. 4,000 square miles. You can see, you know, no obstructions

to the sky. But the reason this is a good place to watch clouds is because in the wintertime,

when it's the wet season, it can get flooded; all right? Heavy rains, and you can get the

whole area of the salt flats with one inch of water over it. And this being so still,

this water surface acts as a perfect mirror to the sky. So being out on the salt flats

is to be suspended in cloud cuckooland. But in fact, it's not the best place to watch

clouds because the best place to watch clouds is wherever you are. It's in your backyard.

From the window of a plane. When you're on holiday and on vacation, from the beach.

And clouds are the most egalitarian of nature's displays. We all have a fantastic view of

them. So it doesn't matter. You don't have to go somewhere special to see special clouds.

You just have to pay attention to the sky. And that is something that climate scientists

have realized we need to be doing more of: Paying attention to the clouds. Because the

role that they play in regulating temperatures on Earth is profound, and it's also complex.

It's not straightforward. The low clouds, those cumulus I talked about

at the beginning, they have the effect of reflecting away more of the sun's heat than

they do trap in the Earth's heat. The high clouds, those wispy Cirrus, they

don't trap reflect so much of the sun's heat away, but they trap more of the Earth's heat

in. So one's cooling and one's warming. And here's the problem. We don't know, as

temperatures change on Earth in the future, whether that means there will be more clouds

or fewer clouds. We don't know whether the effect will be greater on the low clouds,

the cooling ones, or the high clouds, the warming ones. And only when we better understand

the role that clouds play in regulating our climate will we have any chance of understanding

or making competent predictions. It doesn't matter what you think about the causes and

the extent of global warming. The one thing that everyone agrees upon is that the clouds

are the wild cards; all right? Only when we better understand them will we be able to

make confident predictions about what the temperatures will be considered to be the

norm for future generations. So there's a message to take from all this.

What is it? Allowing your thoughts to drift along in the

breeze is something I don't think we do enough of. Our attentions, that's drifting all the

time. Our attention is drifting all the time. We're around the Internet. YouTube, Facebook,

Twitter. With all the feverishness of information addicts.