How Cloudy Is the Earth?
This is a modal window.
The media could not be loaded, either because the server or network failed or because the format is not supported.
Formal Metadata
| Title |
| |
| Alternative Title |
| |
| Author | ||
| License | CC Attribution 3.0 Unported: You are free to use, adapt and copy, distribute and transmit the work or content in adapted or unchanged form for any legal purpose as long as the work is attributed to the author in the manner specified by the author or licensor. | |
| Identifiers | 10.5446/58985 (DOI) | |
| Publisher | ||
| Release Date | ||
| Language |
Content Metadata
| Subject Area | ||
| Genre | ||
| Abstract |
|
00:00
Meeting/Interview
00:17
Meeting/Interview
00:42
Meeting/Interview
01:16
Meeting/Interview
01:34
Meeting/Interview
02:05
Meeting/Interview
02:33
Meeting/Interview
03:14
Meeting/Interview
03:37
Meeting/Interview
04:27
Meeting/Interview
04:43
Meeting/Interview
05:23
Meeting/Interview
05:33
Meeting/Interview
05:51
Meeting/Interview
06:15
Meeting/Interview
06:22
Meeting/Interview
06:43
Meeting/Interview
06:56
Meeting/Interview
07:24
Lecture/ConferenceMeeting/Interview
08:12
Meeting/Interview
08:33
Meeting/Interview
09:02
Computer animation
Transcript: English(auto-generated)
00:04
Well, our main question is, how cloudy is the Earth? You could imagine a really cloudy Earth would be cold at the surface, and an Earth without any clouds would be warm at the surface because it would accumulate much more sunlight. So what we'd like to know is how cloudy is Earth, why, and could it change?
00:23
For instance, as the Earth warms by increasing amounts of CO2, will it become cloudier and warm less, or will it become less cloudy and warm more? Now the way we approach this very big question is to challenge an idea that's been around for 30 or 40 years, that the pattern of cloudiness is controlled by the large-scale weather patterns.
00:42
So for sure, when you look at the large-scale weather patterns, if a storm comes over Europe, it's cloudy, or in the Mediterranean, you'll find many clear days, and that's related to large-scale weather patterns. But if you look in more detail, what you find is on smaller and smaller scales, there's also a similar pattern, Ning, of cloudiness. And the question then is, are the small scales of motion important to say something quantitative
01:05
about how cloudy it is? So what we'd really like to know is how much do these smaller and intermediate scales of motion contribute to determining Earth's cloudiness and how it might change? We have two main methods that we've been exploring recently to try to distinguish whether
01:26
clouds are controlled by the very large scales or if they pattern themselves in systematic ways on the smaller scales. If we go back to the previous line of thought where clouds are determined by the very large-scale fields of motion, then you would expect clouds over very large areas to sort of be randomly
01:44
organized or to have no real patterning because one particular place in that very large area isn't any different than another place in that very large area. Whereas if the small scales of motion play a role, then you would expect to see a systematic patterning on almost every scale or on those smaller and intermediate scales.
02:05
So the methods that we've been developing to answer that question are twofold. One is to try to measure whether the motion fields themselves are homogeneous on these very large scales, as the theory would imply. And the other is when we look at pictures of clouds, do we see regular patterning that
02:24
suggests that there's modes of circulation which determine cloudiness on much smaller scales or intermediate scales? So for the first method, we've been using an aircraft to measure in the atmosphere how vigorous are these intermediate scales of motion, and do they pattern the clouds?
02:43
And in a second, we've been doing things with sort of crowdsourced science and groups of scientists where we collectively come together and we try to visually identify patterning in clouds on much smaller scales and ask if they're recurrent, ask if I can identify a certain type of patterning and give it certain names, will someone else be able
03:01
to identify a similar type of patterning? And if so, can we teach machines to recognize these patterns so that they can give us a global view of how these small scale patterns lead to the large scale cloudiness? Well, what we found out was, no surprise, that the small and intermediate scales of
03:24
motion actually play a really important role in patterning the motion fields which govern how clouds form and are evident in the patterning of the clouds themselves. So in the first line of investigation where we use the aircraft to measure this large
03:41
scale motion field, we expected in a certain situation to find the air gently sinking down with about the same speed everywhere. That's sort of how we approach it until now, theoretically. But what we found was that there was very strong variations in the motion field. And this idea of a large scale motion field moving slowly downward or moving slowly upward
04:04
homogeneously just wasn't at all what we were seeing in nature. We found that there was patternings of motion on much smaller scale where air was going up and down, sometimes in thin layers, that the air would go up in this thin layer and it would go down in that thin layer. And it would be over here, very different than over here.
04:21
And the magnitudes of the velocities were much, much stronger than we ever expected. And these were patterning the clouds. So that's what we found on the one hand with the airplane. And when we looked at the satellite pictures, what we found was that you could find three or four recurrent patterns which had very well-defined small scale structure such that when you looked at these patterns, names and images came to mind.
04:43
We gave them names, four of them. One was called sugar because the clouds fit best this idea of a large scale patterning of the clouds. It was like dusting of sugar on a marble cake with very little structure. But then we saw, if you looked in different days, you would see a structure in the clouds which was much more coarse-grained, like gravel on a dried up riverbed.
05:06
And we called that gravel to represent this coarseness of the features. Others were these beautiful patches where clouds collected in almost like white flowers on a black background. We called those flowers. And others had the skeletal-like feature, which we called fish.
05:23
So what we found was that there was a distinct patterning of clouds on these intermediate scales. And there were scales of motion that we could measure with the aircraft that were associated with these. Who cares? Why does this matter? How is it relevant?
05:40
So if you go back to the original question we have, which is how cloudy is it on earth? Why? And how could that change? For instance, with global warming. It tells us that the puzzle that we're trying to piece together before was missing some pieces. And it tells us what those pieces are. And it gives us an idea of how to use those pieces to fill in the puzzle.
06:05
And so what are the pieces? The pieces are these smaller scales, intermediate scales of motion, which pattern the cloudiness. It tells us that unless we build this into our theory, we can't be confident that we have a global understanding of the things that regulate cloudiness.
06:22
So as we back up and look at the earth as a whole, it might well be that the large scales that we talked about at the very beginning determine these intermediate scales of motion. And those then determine the cloudiness. But if the clouds are linked with the intermediate scales of motion, then they might also have
06:41
a life of their own. But it gives us at least a new avenue to explore how clouds connect to these big questions of how bright, how cloudy is our planet, and how might it change with warming. Yeah, so where is this all leading?
07:03
To a subtropical island called Barbados. There we have a field station where we've been measuring the types of clouds I've been talking about. We've been measuring them for 10 years, and we measure them from a very small part on the island. But to answer the questions I was posing, how do you connect cloudiness to different scales of motion?
07:21
You have to measure the motion on different scales. So we'll take some of the techniques that I talked about a little while ago with the on different scales with one airplane. And we'll bring another airplane, and we'll try to measure the amount of cloudiness at the same time. And so using the two aircraft, we can say something about the environment in which
07:41
the clouds form on many different scales and the amount of cloudiness that you find in that environment. And we can connect those to the patterns that we discovered, these fish and flower and gravel and sugar, and see if they behave differently when you look at one pattern as compared to when you look at another pattern.
08:01
Well, with this core, these two aircraft, one flying high and measuring the large-scale environment and another flying in circles low, measuring the amount of cloudiness, we create a wonderful laboratory to address lots of other questions about clouds, how clouds are influenced by dust particles in the atmosphere, how clouds are influenced by small-scale ocean eddies, how the island might affect the clouds or other aspects.
08:24
And because of that, a lot of groups have come together around this experiment to pursue their other ideas about factors which might influence cloudiness. So in January of 2020, we'll be heading to the tropical oceans near Barbados with the German aircraft, a French aircraft, the British are coming with a smaller aircraft,
08:43
and the Americans are joining as well with an aircraft from NOAA. At the same time, we'll have four research ships, which will spend a month in the seas around Barbados, and lots of autonomous vehicles flying around, swimming through the ocean, measuring almost every aspect of the environment which people think regulates clouds on the large scale.