Science Friday - Greenland Plants, Privacy and Big Data, Rainbows. March 19, 2021, Part 2

Episode Date: March 19, 2021

Under A Mile Of Ice, A Climate Clue Scientists studying sediment taken from a core sample of the Greenland ice sheet just 800 miles from the North Pole have found remnants of ancient plants, freeze-dried under more than a mile of ice. Using several different dating techniques, they say the soil, twigs, and leaves date to sometime within the last million years—probably on the order of several hundred thousand years ago—a time when Greenland’s massive ice cap did not exist. The finding that the ice sheet may have been missing so recently in geologic time provides clues to the stability of the ice, and just how sensitive it might be to modern global warming. The samples themselves have an unusual history. In the 1960s, the US Army set out to build a base under the surface of the ice in Greenland. Ostensibly, the outpost, named Camp Century, was to be used for research into polar conditions, and how best to work in them. In reality, the US also hoped to secretly bury nuclear missiles under the ice cap within close reach of the Soviet Union. As part of that effort, codenamed Project Iceworm, core samples were taken of the ice and sediment. Year later, those samples would become the basis for this climate study, reported in the journal Proceedings of the National Academy of Sciences. Drew Christ, one of the authors of that report and a geologist at the University of Vermont, joins Ira to talk about the study, and explain what ancient dirt can teach us about the future climate. Decrypting Big Tech’s Data Hoard The era of Big Data promised large-scale analytics of complex sets of information, harnessing the predictive power of finding patterns in the real world behaviors of millions of people.  But as new documentaries like The Social Dilemma, Coded Bias, and other recent critiques point out, the technologies we’ve built to collect data have created their own new problems. Even as powerhouses like Google says it’s done tracking and targeting individual users in the name of better advertising, educational institutions, housing providers, and countless others haven’t stopped. Ira talks to two researchers, mathematician Cathy O’Neil and law scholar Rashida Richardson, about the places our data is collected without our knowing, the algorithms that may be changing our lives, and how bias can creep into every digital corner. The Rainbow Connection—To Physics You may have seen a double rainbow, but did you know there are moonbows at night, and even white rainbows? And did you know, if we stood next together to watch a rainbow, the colors we see are coming from two different sets of droplets in a rain shower. That means each of us have our own unique rainbow. This all has to do with the optics, physics, and atmospheric science, which Steven Businger studies at the University of Hawaii Mānoa. Rainbows have captured many people’s attention (including Ira’s! Check out the cover of his book featuring rainbow science below). There is equally fascinating physics responsible for those multicolor beams, which Businger describes in a recent study published in Bulletin of the American Meteorological Society. Businger talks about the science behind rainbows, and discusses why Hawaii might be the rainbow capital of the world.  Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

This is Science Friday. I'm Ira Flato. Later in the hour, a look at privacy in the digital age and the science of rainbows. But first, a trip to the frozen north. On the top of the world, below the surface of a giant ice cap, a city is buried. It was called Camp Century, built in the 1960s, when this army propaganda film was made. Today on the island of Greenland, the United States Army has established an unprecedented nuclear-powered Arctic Research Center. The Army also hoped to secretly bury nuclear missiles there. This is an ideal Arctic laboratory. For more than 90% of Greenland is permanently frozen under a polar ice cap

which covers all but a few coastal areas of the island. As part of Project Iceworm, they drilled core samples deep into that ice cap. In this remote setting, less than 800 miles from the North Pole, Camp Century is a symbol of man's unceasing struggle to conquer his environment, to increase his ability to live and fight if necessary under polar conditions. Today, of course, those polar conditions are changing. The ice is melting. The camp itself is no more. And those core samples are tools in an effort to better understand climate change.

Writing this week in the proceedings of the National Academy of Sciences, researchers describe what they saw when they look closely at the course of, samples taken from deep under the ice in the 1960s. They saw not barren rock, but bits of freeze-dried twigs and plants. It meant that sometime, within the last million years, the ice was gone and the climate quite different than today. Joining me to talk about this as one of the researchers on that project, Drew Christ, is a Gund postdoctoral fellow and lecturer in the Department of Geology at the Gund Institute for Environment of the University of Vermont in Burlington. Welcome to Science Friday. Thanks so much for having me, Ira. You're welcome. When you looked at those samples under the microscope,

give us an idea of what you saw. Oh, gosh. Well, it was just one of the most exciting days of science that I've gotten to be a part of. We were preparing these samples of frozen soil, and we weren't expecting to find any biologic remains. And so Paul Bierman, my co-author and I, were in the lab rinsing away these soil samples, and we saw these little floating black specks in the water. And we're like, what is that? And took a little pipette, sucked a little bit up and looked at it in a microscope. And we just were totally shocked because we saw these twigs and delicate little leaves that were just perfectly preserved. And they had been under almost a mile of ice.

And it looked like they died yesterday. It was amazing. Really? Really? Really. But in fact, how many years ago had they died? So our estimates right now place it to less than the last million years, but likely hundreds of thousands of years.

Could you actually make out the cells inside the plants? Yeah. So with a more high-powered microscope, we were able to see the actual cellular structure in the leaves of these ancient tundra plants. And we actually went to use a scanning electron microscope. and we were able to see just the incredible texture of the woody tissue and leaves that were on these freeze-dried fossils. Could you tell anything about what kind of plants they were? With the help of some of the co-authors on our study who are experts in Arctic plants,

they determined that these are Arctic tundra. So they are small like Arctic willows and mosses that grow in the high Arctic today. Just to get back to your statement about freeze-dried fossils, these are not the kinds of fossils we normally think of dinosaurs, pieces of rock. These are actual just the plants that were freeze-dried. It is not like going to the Museum of Natural History and seeing a giant dinosaur bone in rock. These are more like twigs that you might see like in your hiking boot if you went for a hike in the mountains or something and got stuff from the forest in your boot. I mean, it really looked like it was from yesterday, but we know it was so much older. That's just incredible. I know you didn't go into this looking for plants. What were you after?

That's right. That was the surprise. What we were really after is we were trying to figure out how old the sediment was. And we did a variety of different tests to do that. And one of those ways was to figure out how long the soil has. have been buried. And the way that we do that is by counting atoms that accumulate or form in rocks and sediment when they're exposed to radiation hitting the earth from outer space. And over time, those little atoms accumulate to a point that we can measure it. And if you bury it under an ice sheet for hundreds of thousands of years, they decay away. And we can use that radioactive decay to figure out how long ago they formed. And why couldn't you use carbon dating for this? We always hear about carbon dating.

We tried carbon dating on our little fossil twigs, but carbon dating relies on the amount of radioactive carbon that is in dead organic material. And all of that radioactive carbon will decay away after 50,000 years. So when we tried that analysis, we got answers saying there's no more radioactive carbon left. These are older than 50,000 years. There's a technique he can use to tell how long it's been since some soil has been exposed to light, I understand. How does that work? Yeah, this is a really cool technique. And the way that this works is that there is background radiation in all of the materials on Earth's surface.

And when a crystal is buried below the surface, there are these little holes inside of that crystalline structure that will become occupied by the radiation. the background. We can go into a lab in the dark and then re-illuminate that sediment with light and measure how much radiation comes out of that sediment and figure out how long ago it has been exposed to sunlight. It's a pretty involved in technical method, but it's another way that we have determined how old these soils are. I understand there's a kind of analysis that you can do on the water that tells you about the elevation. Can you, can you describe what you found there? Yeah. So what we did there is that this soil, when it came out at the bottom of this ice core, it's like sands that are held together by frozen ice, and we thawed that ice and then took the

melt water from it. And we can analyze different isotopes of oxygen in that water. And those isotopes with oxygen will tell us things about how warm or cold precipitation was in the past, as well as the elevation that it fell at. And so the results we got from that analysis tell us that the precipitation that fell at this part of Greenland was much lower in the past than it is today. Right now, the elevation of the ice sheet is about 1900 meters. And our analyses tell us that elevation was about 900 meters lower based on these analyses of the water. So that ice sheet was really much thinner back then? It was gone.

So it was the, all of that ice must have disappeared in the past to allow precipitation to fall at that elevation. And it was slightly warmer, too. So that's one line of evidence that this part of Greenland was ice-free in the geologic past. And how long would that geologic past be? within the last million years from the other ways that we've determined the age of this soil. And we are still working to figure out exactly how long it was gone. And that'll be really important information for understanding how sensitive the greenland ice sheet is to climate warming. Does that mean that the ice sheet melts and refreezes many, many times since the last, what, a million years ago?

Potentially. That is an important thing to consider, because if, the Greenland ice sheet has been able to survive through fluctuations in Earth's climate over the last million years, then that means it is more stable. But if it disappears, and we know it's disappeared at least once, and perhaps multiple times, that means it's quite sensitive to minor changes in climate. Over the last million years, carbon dioxide in the atmosphere hasn't gotten much higher than about 285 parts per million. And right now, because of human burning and fossil fuels, we are in excess of 410 parts per million. So we have completely changed the climate system. And we are, let's just say we are going into uncharted territory.

Well, we know that Antarctica is melting now and that Greenland is melting quite rapidly. Why is it so important to know that this happened before? It's really important to know that this happened before. happen before because it allows scientists to understand what climate conditions cause the ice sheep to melt in the past. And if we know what conditions allowed ice to melt in the past, it helps us understand in the future what the limit is to climate warming. So that's why it's so important to understand how these ice sheets have been sensitive to climate change in the past. Do we know that past melting and freezing took place at the same rate that it's happening today,

as quickly as it's happening today, or was it much slower? Well, that's also a really important field of research as well, is trying to figure out in the geologic past how quickly ice sheets have melted. In the past, these melting events would take thousands of years to occur. But as we move into the future and we increase the temperatures on this planet, more rapidly than would naturally occur in the past, those thinning and retreat rates of the ice sheets could be faster. And that's something we want to avoid because it would result in more sea of a level rise over a shorter amount of time. The absence of a layer of ice in Greenland

that you talked about before, do we know if that was connected to what might have been global warming in those days? So the absence of the ice in Greenland within the last million years may be due to periods of time where Earth's climate was slightly warmer than it is today, but it was warm for really long periods of time. And so what we are worried about in the future is that if we warm the planet so much for such a long period of time that we could cause additional melting of these ice sheets. An analogy that I think is helpful for people to think about is if you go to a barbecue in the summer and there's a cooler of drinks with ice in it, and you leave.

that cooler open for maybe half an hour, you'll probably still have ice in the cooler. But if you leave that cooler open for eight hours and then it gets up to 95 degrees, you're probably going to melt all of the ice and you'll have warm drinks. So that's what we are worried about is keeping the earth too warm for too long and melting the ice. We've run out of time, Drew. Thank you for your great questions. Well, thank you for your great answers. Drew, Chris, is a gun postdoctoral fellow and lecturer in the Department of Geology at the Gund Institute for the Environment at the University of Vermont in Burlington.

We're going to take a break, and after we come back, why a lack of privacy online is just one problem in a world increasingly driven by big data. This is Science Friday. I'm Ira Plato. One of my favorite sayings is the road to hell is paved with good intentions. And when the internet was unleashed to the public, I assume that the designers of e-mails, social communities, smartphones and watches, had the best of intentions, wonderful, fun meeting places where we could gather to meet and greet and discuss stuff. I was willing to sign those multi-page user agreements

in exchange for the services of this brave new world. But somewhere along that road, the Internet became very commercialized, all about the money, collecting details of your life, tracking your movements online and where you walk, and whom you'll talk to, selling all of this big data unregulated to advertisers, government agencies, and whomever would pay for it. It became evident that I was not the customer.

I was the product. The more I investigated, the more troubled I became about biased algorithms, democracy, and social justice. I wanted to talk to some of the people who've been sounding the alarm about the harms of big data collection and the tools used to pry into our private lives. So I've asked a couple of them to be on our show today, and let me introduce them. Professor Rashida Richardson, a visiting scholar at both Rutgers Law School and the Rutgers Institute for Information Policy and Law, and Dr. Kathy O'Neill, mathematician, data scientist, and author of the book,

Weapons of Math Destruction, How Big Data Increases Inequality and Threatens Democracy. She's CEO of the Algorithmic Auditing Company, Orca. Welcome to Science Friday. Thanks for having us. Yeah, thanks, Ira. Let me begin with one of the reasons I felt I needed to talk about this was the phrase, as I said, you are not the customer, you are the product. Rashida, I mean, is that how we are now?

In some regards, yes. But in many regards, it's that we have a limited economy of choice. We have to use many services and products that do collect a lot of our data to then commodify that data, but there seems to be less and less choice amongst consumers about whether or not you can opt in or out. Kathy, how do you react to that? Yeah, I mean, I think about it similarly. When I was studying when I was doing my research for my book, Weapons of Math Destruction, I focused on the algorithms that we interact with by necessity. Like when we try to get a job, when we go to college, when we get insurance, apply for credit or a mortgage. Like,

we don't have the option to not be judged by an algorithm in those situations. And we don't have the option not to have our data used against us or for us. They profile us and deciding whether we deserve these things. We can think about opting and or opting out of certain types of things. But for the most part, we always will interact with those bureaucracies and those bureaucracies will be run by algorithms. Your work is looking at sectors we might not expect our data being used against us, Rashida, as tenants in rental housing, even education context. Can you say a bit more about this? Yeah, there's a lot of data that's collected on a daily and annual basis by government entities through administrative practices, and they also get access to private data, and that data

can be used and applied to make decisions regarding where students are assigned to go to school, whether or not you're eligible for public benefits and the amount of public benefits you should receive where police will patrol or who is likely to be a criminal, which children are likely to be subject to abuse. And these are all decisions that, one, are highly subjective and high risk. But two, I really question whether or not data enables us to make more informed decisions about. And often when applied in algorithmic systems, there's a level of opacity that then makes highly subjective and often discriminatory decisions less visible and sort of reinforces this notion of these decisions being fair and neutral. Give me an example, Kathy, if you can,

of how our data is used against us. Well, the FICO score, you know, the credit score that we're all used to. You know, that's sort of like an old school version of data being used against us, if you will. It's kind of reasonable in a lot of instances that it's being used because it tracks whether we're paying our bills. There are all sorts of new fangled versions of classical credit scores, and they are being used with all sorts of kinds of data, like our social media data, who we're friends with, what our chances of getting sick are, what kind of illnesses we might have. the way data protection works in this country, as long as it's sort of available for sale, it's not considered protective medical data. It's allowed to be used pretty much by anybody

to decide our options. Rashida, let's go back to some news that came out recently, and that being that Google says that they will no longer attract individual users. They want to face out cookies and use more anonymous groups or categories to target ads. So we'll get some privacy back, right? Is that good news, Rashida? I mean, it's good news that they recognize their data collection practices are problematic, but I don't think this one change in policy and practice is now going to make it so that we all have greater privacy protection. Google has been around for over two decades. All of the data that they've collected over that time,

they still have and they can still use in a variety of ways. And there's also a lot of ways that Google controls the data that we are able to see or have access to. And that constrains a lot of our choices and opportunities available. Kathy, you've written about targeted ads themselves as being bad for us. Why is that? A lot of people do want targeted ads. I personally enjoy all the glistening gem-colored yarns that I'm offered on a daily basis because they're beautiful. So it's not always a terrible thing.

I think there's sort of two exceptions to this as a service that we need to consider. And the first one is a lot of the ads are actually predatory. Like the way the online ecosystem for advertising works is it gives services to lucky people. So it makes lucky people luckier, if you will. And then it preys on unlucky people. So it makes unlucky people unluckier. And the way you see that is you can see gambling houses will sort of pray on people that might have gambling addictions. You'll see same things with for-profit colleges.

They specifically micro-target people that don't really know the difference between private colleges and for-profit colleges and don't know that they're not going to get as good in education. There's the predatory side of it. And then the other thing that we have to keep in mind is that the political landscape for political campaign ads, that microtargeting, that has a different problem, which is a little bit harder to measure, but it essentially is destroying democracy, if you will. You just can't say that and not tell us more about that. Oh, it's destroying democracy, if you will. In what ways?

The most obvious way is because the political campaigns have all the control, they have all the information about the people, they can literally tell one thing to one group of people and another thing to another group of people. They could actually just say different things about the candidates' policies. Now, I don't think that happens too, too often, but what I do think happens is they choose different things to show the different kinds of people. Basically, what it comes down to is instead of the voter becoming informed, they are exposed to the very things that the campaign wants them to be exposed to and to nothing else. And that includes that it might not even be information at all.

It might be simply emotional manipulation. And if you want to go to an extreme example, think about the way in 2016 we discovered after the election that Trump's campaign actually suppressed the African-American vote with micro-targeted ads on Facebook, trying to convince black voters do not vote. It's not worth it. Yeah, that's certainly an example. And going back, Rashida, to this decades of data, Google has stopped collecting some data now. But how many other places on the Internet, do we still have to worry about our data being scooped up without us knowing it? Well, I think it's better to understand data collection and consumer surveillance on maybe a sector level and that it's not all on the internet. We have data collection and surveillance happening in financial services, as Kathy touched upon, telecommunications, all our location data is tracked.

And then basically in any physical environment we're in, our information is being collected, whether it's a workplace, school, or even our own home, depending on which type of listening devices you have in your home. Not to mention facial recognition. That's why I said basically any physical space in public spaces. We have tons of CCTV cameras and other technologies that can collect both aggregate data about us, as well as very minute and personal data. And all these companies, they make big money off of selling this data,

shouldn't they be paying us back something for the use of all that data? Well, I think it's a little more complicated because you also have to understand that while there is some data that is very specific to us as individuals, a lot of data is relational. So simply saying that each of us as individuals can own data and then sell it on an open market is not necessarily a solution either because that tends to reinforce any type of social inequities that exist in society and that as a black woman, I know my data is not going to be worth the same as a white man. And what does that mean when there's different values to data and the primary means of protecting it is selling it? You know, Rashida's point about how much is

my data worth? I mean, one of the things I discovered in my research for for-profit colleges, and those for-profit colleges often targeted single black mothers. Those clicks were worth a lot of money. I'm not saying that white man's cliques are not worth money. I'm just saying that, like, you'd be surprised. I think the real issue is that the bargaining power isn't there, right? The bargaining power of most of the people in society, they don't have the time nor the understanding of what their data is worth to actually make the negotiation work in their favor. It points to a larger problem, of course, which is that going back to your imagination, Ira,

at the beginning of what the Internet was going to be. On the internet, we are not citizens. We are consumers. So it's all about money all the time. If we go in there thinking we're in a town square being able to have a conversation, we're wrong. We are in a rented space and we are paying that rent with our data. And it's important that we understand that, Kathy, right? Yeah, we have to understand that because one of the trickiest things is how do we change that?

What's a new vision where it is more like a town square? We're not being constantly measured and sold. Does that talk about government regulation then? Is that one of the pathways that we might head, Kathy or Rashida? I think we need multifaceted approaches because, yes, government regulation is one part of this conversation in that you can regulate the tech sector or even enforce antitrust regulations to have specific outcomes. But I think the reason why there's not a simple silver bullet solution to all of this is

because some of this comes down to societal value. So if we only believe in like rugged individualism and free markets as means of addressing everything in society, then that shuts out a lot of marginalized communities and individuals or allows for more predatory practices and situations to emerge for certain groups. What about cities and states then that have talked about banning facial recognition or banning certain kinds of algorithms, Rashida? I think those are necessary steps in that there are certain technologies like facial recognition in some forms of predictive analytics that have only demonstrated harm in society. But I don't think this sort of whack-a-mole approach of banning or putting moratoria on the most egregious examples of bad technology is necessarily our way out of this because some of

this stems from structural inequalities in society and not all of these problems. are specific to just technology, but they amplify and compound a lot of the problems that have pre-existed in society. I would even argue that we don't need new laws so much as we need to enforce existing laws. One of the things that kind of kills me about algorithms is that they are currently bypassing a lot of really important anti-discrimination laws in the regulated sectors of insurance, credit, and hiring simply because the regulators don't know how to decide whether an algorithm is compliant. And by the way, the answer is no. It's probably not compliant. That's actually what I do in my day job. I audit algorithms for things like, you know, racial bias and gender

bias and things like that. And since the data is biased, the algorithms are biased. So all I'm saying is that instead of thinking about like what new laws do we need, I would start with what about enforcing the existing laws that we have. But I actually want to complicate this a little because I think there's also problems with how we view some of these problems. So a lot of the anti-discrimination laws are based on intentional discrimination or discriminatory intent. And that's just a problematic framework in that there's tons of discrimination that happens in our society on a daily basis, where if you ask the person who's actually discriminating, they wouldn't be like, that wasn't intentional or that wasn't my intent. I agree with Kathy in that I do think we have some laws that

just lack the enforcement. But I also think some of our legal frameworks really need to be revised and not only in light of our sort of big data society, but being realistic about how societal problems like discrimination actually operate in society. Just a quick reminder. This is Science Friday from WNYC Studios. Kathy, you wrote your book, Weapons of Math Destruction in 2016, and this year, Netflix documentary, like the social dilemma and the upcoming coded bias. They're trying to act as wake-up calls about the downsides of the digital age. Is there something special about this moment in time that these wake-up calls are getting louder and more prominent?

I think the answer to your question, Ira, is that the obvious failures of some of the algorithms are becoming so much more obvious. It's undeniable and they're becoming a PR fiascas. So facial recognition is an example where it's. it gets to be pretty clear how it's being used and how it's failing. Thanks in a large part to the work of Gender Shade Study with Joy Bolamwey and Deb Ragi and Tim Nookabrew, by the way, I would also caution, though, that there's a lot of problematic algorithms that are not public-facing, that are really problematic, and we aren't hearing about them. And Rashida, are people paying

attention to the right problems in digital surveillance or algorithms? I mean, what would you want on lawmakers' minds as we talk about reforming tech? I think just what Kathy said to have a more expansive view of what the nature of the problem is, I think a lot of our public discourse is about private sector practices and uses, but a lot of my research and what I think is the worst stuff is what's happening in government and in the public sector, because often we see data surveillance and data applications being used to make high-stakes decisions about people that can completely throw off the trajectory of their life or inhibit any type of opportunities they have access to.

And I think the way we often talk about data as well presumes this level of objectivity or that the data reflects reality in some ways rather than it being very valuated and subjective. And then that type of subjective framing of data is applied in. circumstances where it feels like fair or more neutral decisions are being made. And there are no neutral arbiters, whether it's an algorithm or a judge. And I think we just need to be a little bit more honest about those realities. You know, we've been talking about this for quite some time now. And I would like to thank both of you for taking time to be with us today. Thanks, Ira. Thank you, Ira. Professor Rashida Richardson, a visiting scholar at both Rutgers Law School and the Rutgers Institute,

for information, policy, and law. And Dr. Kathy O'Neill, mathematician, data scientist, and author of the book, Weapons of Math Destruction, How Big Data Increases Inequality and Threatens Democracy. She's CEO of the Algorithmic Auditing Company, Orca.

After the break, why are there so many songs about rainbows? Maybe because there's lots of interesting science and how they form and what we see. Hi, everybody. Ira here. I can't believe it. but it's been one year since Science Friday and much of the country started working remotely. It's been hard, right?

We miss seeing everyone. I miss the studio. And mostly, I miss being able to talk directly with all of you, our fans. It's also been difficult to fundraise. So if you have a minute and a dollar, please consider making a gift to support our program. Go to sciencefriiday.com slash give. Hopefully, we'll be all together again soon. Until then, stay safe and thank you.

This is Science Friday, I'm Ira Plato. Who among us doesn't stop and marvel at a rainbow? It is really a wonder of nature, and if you don't believe me, just ask the double rainbow guy. Whoa, that's a full rainbow all the way. It's a double rainbow all the way. Whoa, a lot of enthusiasm there. And the double rainbow is just the beginning.

Did you know there are moon bows at night? And yes, there are even white rainbows. And how about this? Each of us has our own rainbow. The one I'm looking at is the different than a rainbow you're looking at standing next to me. We'll get into all of that, the science, the magic behind these majestic multicolored arc forms. My next guest is here to be our rainbow connection. Get it.

And to tell us all about rainbow. and why Hawaii might be the rainbow capital of the world, and there's an app that will let you become a rainbow hunter, if you'd like. Let me bring on a man who had a double rainbow for breakfast, he tells me. Steve Bousinger, Professor of Atmospheric Sciences at the University of Hawaii in Manoa. Welcome to Science Friday. Thank you. I'm thrilled to be here. I'm a big fan of your show.

Amazingly, I woke up this morning, looked out the window, and there was a spectacular double rainbow right out of the world. outside my window. Thank you. Nice to have you. Just a quick note to our listeners, our segment is being recorded with a live Zoom audience, and you all can learn more about joining a future live recording at ScienceFriday.com slash live stream. I think it's great that you had a double rainbow for breakfast because I love rainbows. They are works of nature, but they're also works of physics, right? Tell us how a rainbow works. Where did the colors come from? How does all of this happen? Well, you need sunshine and you need some rain, and that's the combination which we get a lot in Hawaii.

The sunshine, it goes into the raindrop. It refracts as it goes in. It reflects off the back of the drop, and it refracts again as it comes out. And in the process, the light from the raindrop has an angle of 42 degrees from the incoming sunlight. And that is the angle of the rainbow. and it is this refraction that is different for different colors or wavelengths of light that separates out in the process to produce this gorgeous rainbow. And so things have to be very specific.

You have to get that 42 degree angle, right? You have to have the sun behind you. That's right. You have to have the sun behind you. And if you look at the shadow of your head when you're standing looking away from the sun, the shadow of your head, that's the point where you measure. 42 degrees from. And the funny thing is your friend who's standing next to you, the shadow of his head is the center of his rainbow. And that's why no two people see exactly the same rainbow,

because each rainbow comes out from the shadow of your head at 42 degrees. So the raindrops that are falling down as they're making the rainbow are different for me than they are for you. That's what you're saying. The colors are coming from a different set of droplets. and therefore it's two different rainbows, essentially. That really is cool. So if the rain droplets are falling, we get that Roy G. Biv sort of color, right? Sir Isaac Newton, who explained the dispersion of the colors

and actually came up with spectrum, that word. And he decided that there were seven colors in a rainbow. And it turns out that the seven colors is a bit arbitrary, But it does follow along with the seven days of the week and the seven major planets and the seven musical notes in an octave. So he felt that that was really compelling, that there ought to be seven colors. But the human eye can see many, many more colors than seven. Let's talk about the ingredients for a rainbow. What are the environmental conditions that you need for a rainbow to form and for anyone to see it?

Right. You know, it's interesting because a place like Seattle or London gets lots and lots of rain, but they don't get as many rainbows as Hawaii. And the reason is that you need to have rain falling out of relatively isolated showers with lots of ability for the sunshine to get in on the side. And another thing that we have in Hawaii, plus the fact that we have these isolated showers, trade wind showers that are called, is that. that we have mountains. And the mountains enhance those showers. As the air comes down on the lee side, it causes the cloud to evaporate and have sunshine. So in the town of Honolulu, which is on the lee side, you look back towards the mountains in the afternoon, and there are lots and lots of these showers creating rainbows.

Let's get into this double rainbow question. We started out this segment on double rainbows. Let's go to our first listener question. Barry has a question about the rarity of double rainbows. Yes, double rainbows. How common are they? And can you have rainbows that are triple or even more than that? Oh, yeah, good question.

What do you say, Steve? That's an excellent question. It turns out that double rainbow is the product of two reflections at the back of the drop. The primary rainbow has one reflection and the double rainbow has two reflections. and it comes out at 51 degrees instead of 42 degrees. So it's a little higher above the primary boat. And because there's an extra reflection, the colors are reversed with red on the bottom and indigo on top.

There are possibilities for more internal reflections, and therefore there is the third rainbow and the fourth rainbow and a fifth rainbow, et cetera. But with each reflection, you're losing a bit of light out the back of the drop. And so it's very rare to be able to see these other rainbows. The third rainbow create a big circle around the sun. And then the fourth rainbow goes back in on the other side. And in the last few years, it turns out with all these digital cameras and people taking

photographs, that there actually have been some photograph, some photographic evidence of these tertiary and quaternary rainbows. It's really fascinating. Wow. There's so many things about rainbows that are fascinating. For example, I hear that you can have rainbows that are a single color. Is that right? How does that happen? Well, let's say that there's just a little bit of volcanic emission that happens in Hawaii. We get a little bit of foggy aerosols in the air that scatter the blue light and the green light out. And so what's left is this reddish orange light. And when that hits the rain, it produces a red rainbow. Now, on the other side, there is a possibility to get a white rainbow too. And we call that a cloud bow or a fog bow, depending on what the cloud is that's

producing it. So in that case, you have, the droplets are small enough so that there's enough me scattering going on and there's a blurring of the colors and since they all kind of blur together they become white light again that gives you a white rainbow and the interesting thing is that the Hawaiians had a saying that if you saw a white rainbow it was good luck it meant prosperity that's quite interesting and rainbows at night do we have a special name for them well moonbows of course moon bows yes the moon bow is restricted because we don't always have a full moon. And you need a lot of light from the moon in order to create a moon bow. The human eye is less able to see color when the light is very dim.

You know, think about a car driving by at night. You know, it may be red, but it kind of looks black. So the moonbow has less distinct colors than the rainbow does. However, digital cameras now can create some beautiful photographs of moonboes. So it's definitely worth. going out and looking. Now, I understand that you have a study that makes the case that Hawaii is the rainbow capital. Tell me what conditions make Hawaii the capital for rainbows. It turns out that there are lots of reasons why Hawaii is special when it comes to rainbows. I've already talked about some of them. The trade winds blow seven days out of ten and bring these isolated showers, which are very perfect for rainbows. The mountains produce updrafts on one side and thinking motion on the

other, so you get rain over the mountains and clear skies in the lee. Another great opportunity for rainbows. Then we have very clean, clear air here, most of the time. We're very far from any pollution sources from dust and pollen that you might have on the mainland. And so the air is pretty clean and that results in very strong sunshine that produces a brilliant rainbow. Now, the last thing, which is related to all that is that the clouds here, because the air is so clean, have fewer cloud droplets. And what that means is that the moisture in the air is going to be divided over fewer individual droplets. And this makes the clouds more efficient at producing coalescence where the rain comes together and produces a rain droplets out of

relatively shallow, small clouds. And so we have lots and lots of this, this rain coming out of small, shallow clouds with bright sunshine coming in. So it's a combination. I love these details. Who knew? This is Rainbow Geek Heaven. It is, indeed. That you're talking about. We talked to Pua Kea Nogelmeyer, who studies Hawaiian language and you worked with, and he talked about how Native Hawaiians describe rainbows.

There's a really high level of specificity in Hawaiian. In English, I think we use rainbow a great deal. There's a rainbow over the ocean. There's a rainbow of, you know, so it's a different specificity, I think. Also, the notion of... That's sort of culturally defined, blue, indigo, and violet, into a single, with intensity as with color distinction. And he had this to say about these observations as science.

It kind of overlaps almost in the sense of citizen science, right? Isn't science just observation that's verified over repetition and collection of data. You know, this is science data, whether it's scientifically approached or simply as an observer. approach. Yeah, Steve, how did you work with all that scientific citizen science data? The ancient Hawaiians were keen observers of the natural environment, and their survival really depended upon that kind of very careful observation. They had names for winds coming down different valleys and from different directions, so they have hundreds of names for different wind. They have many, many names for rainbows. I mean, I just went to the dictionary and pulled out

20 names, but it turns out there are many, many more. And from these citizen science articles that were published in the newspapers, we discovered that there was a category four hurricane that hit the Big Island and Maui in 1871. We could see exactly what the track was. We knew what the damage was by the descriptions of what happened to the trees and so forth. And it made a difference in how we think of hurricane risk in the Hawaiian Island. So these citizen science observations have real implications. That's amazing. That's really cool. I'm Ira Flato and this is Science Friday from WNYC Studios. Let's go to a next question from listener Renoir has a question about rainbows on other planets. Yeah, I'd like to know that. Go ahead. I just had a question about how a rainbows.

might look on another planet. I guess you wouldn't really know because we haven't really seen one, I don't think. But I was curious about how the sun, various sun and their wavelength frequencies might affect how a rainbow would look. And also, do you need water droplets or could you have other chemicals or whatever in the atmosphere that would create a different type of rainbow? Thanks. Great question. What do you say to that, Steve? That's a wonderfully inventive question, and it shows a lot of creativity. I haven't really thought about that, so this is just off the cuff. Certainly if the sun or the star that this other world is orbiting around has a different color than our sun,

and it also depends on the eyes, how they have developed in the life form of this other planet. Of course, if we travel there, then it would be our eyes. But, yeah, there certainly could be other kinds of precipitation and different refractive index associated with that. One could imagine maybe do a little bit of research on this to make a case for a different look of a rainbow on a foreign world. I think it's really intriguing. Yeah, so if it's raining nitrogen or something, it's going to look a whole lot different. or methane or whatever it is. And we're running out of time,

but I want to get to something I've been dying to talk to you about. I know you're creating an app called Rainbow Chase to help people track where a rainbow might be. It sounds to me like tornado tracking, but you're doing it with rainbows, finding a rainbow forming.

Yeah, you know, a friend of mine, Paul Sin, he's absolutely nuts about rainbows. He's actually originally from the South Korea. and in Korea, when they see a rainbow, it makes the nightly news. And so he and I dreamed up this idea of photographing a circle rainbow from a helicopter. And we needed to know where to go with the helicopter. So I said to myself, why don't we create an app for a smartphone where we can give the helicopter pilot some guidance as to where he should. fly to get this circle rainbow. And that's sort of described in this paper that I published.

But the rainbow app is actually available and you can download it. Just to type in Rainbow Chase and you can download it for free and it will remain free because our goal is to bring more rainbows into people's lives. Unfortunately, at the moment, it's only available in Hawaii in terms of, so if you download it, you'll see Hawaii and you can look at where the rainbows are in Hawaii, but we are planning to expand it to the mainland. And that's our goal. So if you want that rainbow connection on your app, you've got to go to Hawaii to use it. That's right. For now, but in the future. All right. I'm looking forward to that, and I'm very happy that you took time to talk about us about rainbows today, Steve. It's been all a lot of fun. Dr. Stephen Bousinger is Professor of

Atmospheric Sciences at the University of Hawaii in Manoa. And if you want to see photos of these double rainbows, the 360 bows and more, you can get your rainbow fill at our website at ScienceFriday.com slash rainbows. And if you want to learn more about joining a future live recording, like we're doing now, go to our website, science friday.com slash live stream. That's about all the time we have for this hour. if you missed any part of the program or you'd like to hear it again, subscribe to our podcasts or ask your smart speaker to play Science Friday.

And of course, we're active all week on social media, Facebook, Twitter, Instagram, or you can email us SciFri at Science Friday.com. I'm Ira Flato. We'll see you next week.