 This is Think Tech Hawaii, Community Matters here. Good afternoon and welcome to another episode of Likeable Science here on Think Tech Hawaii. I'm your host Ethan Allen. And with me today is Dr. Allison Nugent. Welcome Allison. Thank you. Allison is a professor in the Department of Atmospheric Sciences in SOS, the School of Ocean... Ocean Earth Science and Technology. Ocean Earth Science and Technology. I can never remember that. They're at UH Mānoa. Fairly new here. You came here, I guess, in 2017 after a very stellar graduate career. Undergraduate at Harvard. Graduate at Yale. Both a master's and PhD. One presentation awards and best graduate student award or something like that. Has various, all kinds, multi-talented. She's developing a course with Python and Matlab to help get computing sciences into the work you do. Fascinating stuff. But, you know, Likeable Science is all about how science is useful and applicable to our daily lives. And so that's, of course, what we really want to talk about. So you study clouds, basically. Clouds and mountains really, which are part of our daily lives, right? They're always present in particularly on small islands like this. So what got you involved in it? How did you get interested in this? Did you grow up thinking you were going to go and study clouds? Yeah, that's a great question because a lot of people who study meteorology got into the science by having a storm memory. Maybe some hurricane affected them when they were a child. But that wasn't my story. I just, I love the outdoors and I love being active and I like to look around and see what's there. So I guess I kind of fell into it in college where I liked sciences and the people that were doing outdoorsy things were the ones who were studying earth science. So I went to college thinking I might be a doctor and I ended up being an earth scientist instead. Okay, so if you operate on people, you operate on the planet. You do geo-engineering, right? In particular, you look at the interactions between islands mountains and sort of the prevailing weather patterns, right? Now the mountains influence the weather, right? It's a big and important area, right? Clearly if we in Hawaii did not have mountains here, our weather would be very, very different, right? Yeah, absolutely, very different. We'll see at the very end of the show a map of the rainfall and to see the one very low Hawaiian island, much less rainfall than all the others. So maybe start with a quick talk a little bit about clouds and sort of people don't understand like clouds just appear and people sort of think of them as things that always exist and the clouds come and the clouds go. But they're very dynamic, right? Yeah, I think that's a great point that clouds, they're just always there. They're not something that you often think about and yet they play a huge role in our day-to-day life. So for example, like what are the clouds look like today? Likely cloudy, I would say, but mostly here. Yeah, but you might not notice. Yeah, but if you start to recognize cloud patterns and you keep an eye on them, you can notice weather patterns and you can't get rain without clouds, so that's one. But also the way they look and the way they're shaped tells you a lot about the weather. So that's interesting. I'm going to take a little sidestep here. When I was a child in Florida, there would be, as far as I can remember, completely clear blue skies and it would start pouring rain. Really? You just contradicted what I said. Other people have said that's impossible. It had to have been clouds there. Maybe there were. I just don't, maybe you're not remembering them, but I just remember it would seem to be bright and sunny out and pouring and I guess maybe there were random clouds I wasn't noticing. Was the wind strong? Not particularly, no, just anyhow. So let's talk about what a cloud is. So a cloud is just composed of millions and trillions of tiny little water droplets. They're of a scale that you probably can't see with your own eye, maybe about one micron or 10 microns. And clouds are just an uncountable number of them. A cloud touching the ground is the same as fog, so if you've hiked Kulio'u Ridge or something and you've been in the foggy area, that's a cloud touching you. And you can see it just kind of feels wet, moist. And so what happens is that as air is lifted, it finds air that has lower pressure and so it expands. As it expands, it's temperature cools. And the same thing that happens on a warm, humid day where you have a cup of water that gets wet on the outside. You have condensation occurring where it's cooler. Same thing happens, you have condensation occurring in your cooler air. And so sometimes you can get a cloud that way. Right, it has to condense around something typically, right? True. But that something can be as small as a single crystal of salt or a tiny bit of grit or a dust flak of some sort, right? Yeah, they're called cloud condensation nuclei or CCN and it's just a surface on which water can condense. Right, typically you need something to start the condensation process around right now. So that's very interesting because we think of rainwater which is being very clean and yet you realize each droplet there has to have something other than water in it really. Yeah, and not only that, it takes approximately one million cloud droplets to come together to make one raindrop. So that means there's one million particles of stuff in your raindrop. And yet rainwater still is generally clean, quite drinkable as it follows from the sky. More problems get to be after a tip. Surfaces have started picking up stuff off the surfaces, right? Yeah, maybe a good point to mention would be that while you have that stuff to condense onto, sometimes it dissolves in the water or sometimes it's a gas phase particle. So in the water it may not be like... Grit. Grit, as you described it. It may actually just be dissolved in the water. And indeed, if we drink distilled water, people don't tend to like the taste of it very much because it has sort of no taste at all. You actually want a certain small amount of salt and yes, minerals and things in your water, right? Yeah. So in particular, yeah, you're talking about this and it's called orographic precipitation, right? Which is when the warm moist air rises, expands, cools and condenses into clouds. And that happens typically on one side, in this case in Hawaii, on Oahu here, sort of on the northern eastern front of the mountains, right? Yeah. Because that's where the prevailing winds are bringing in. Yeah, where you have rising air, you'll get a cloud and when you have sinking air, no cloud. And so on the windward sides of mountains where air is being lifted, that's where clouds form. And on the lee sides, like over here in Honolulu where air is descending, you'll have less cloud. Right, and this is why we have, from where I live in Waikiki, we get 23 inches of rain per year or something and just up at the top of the ridge, so I can see from my own eye, they get 150 inches of rain per year or something insane like that. Yeah. And even in this just a three or four mile shift, you've got this tremendous, this whole difference in rainfall because that's high up on the mountains. I think of it as almost combing the water out of the air in a sense, perhaps a bad analogy. Yeah, perhaps. I think it depends on the case. It's called the drying ratio or how much moisture the mountain can extract from the air. And in the tropics, it's typically less than a percent. It's actually been shown that the incoming moisture gets mixed upwards into the atmosphere rather than being rained out. So it's not that there isn't enough moisture left to rain on you when you're on the lee side of a mountain. It's just that moisture has been mixed upwards and so it's not necessarily coming down on the lee side. That's intriguing. Fun fact. I wouldn't guess it only dropped one percent of it. Yeah. Well, in mid-latitudes, it can be much higher. So if you have, for example, the Cascade or the Olympic Mountains in Washington where you have stratiform rain just pressing up against the mountains, those mountains can extract much more, maybe 40 or 50 percent of the moisture. But here in the tropics, because we have clouds that grow upwards and convect upwards in buoyant circulations and motions, then the moisture is mixed upwards instead of raining out. So it's very different depending on where you are on the globe. Interesting. I have a great subtle difference. I have no idea about that. So, and this makes tremendous impacts in terms of what you talked about. It's called the rain shadow, right? That is the dry space on the other side and very evident, for instance, on the big island, right? Where there's a virtual desert on the west side of the big mountains, whereas on the east side, it's quite wet, right? Yeah, absolutely. And again, as you mentioned, the Cascades, right? You drive up the Cascades on one side, it's all dug fur, and the moment you go with the crest, it should become a pine forest and a high altitude desert, right? Yeah. Yeah, and these things are all over the world. Every island, every mountain, every continent with a mountain range has these huge differences in precipitation on one side or the other. So you said what it was, which is orographic precipitation, but I think most people don't know what orographic means. Right. So orography is just kind of another word for topography. It just means precipitation that's controlled by mountains. Okay, yeah. I mean, islands in this particular... Don't have any mountains, like in the Marshalls, they typically get a lot less rain, right? There are ways because those are atolls and there's rising warm air from the shallow lagoons that they generate a little bit of their own weather, but it's nothing like what happens on these mountains. And this is critical particularly for our islands, right? Because this is essentially where all of our fresh water comes from, right? I mean, we have no other fresh water source based on what falls on these islands. And gradually over time, we've sort of filled up aquifers, porous spaces in the rock, open spaces, and that's where we generate all of our water, right? Yeah, that's a great point. Ecosystems and you rely on these and waterfalls and freshwater fish. Right. Like a cloud forest. Do you know what a cloud forest is? Right. These are forests that essentially get all their moisture out of the fog or the clouds that run through them. It's not necessarily from rain, it's from actual cloud touching the plants and, yeah. Right. And there's now people in drier climates are trying to work on similar ideas. They put up dew fences or fog fences to try to do the same thing and get drinking water out. To extract water from the atmosphere without having to make rain. Right. And there are groups that are commercializing this technology in various other ways too now. There's very high tech things. What's a group down in Arizona that's doing this? How blank on their name? They have sort of what look like solar panels but they're actually structured. They're structured with pores in them that are very just the right sort of size and shaped water molecules pop in and then they're cooler on the other side so the water begins to condense almost immediately. That's a good idea. And they can actually pull water out in Arizona, pull water out of the air, which is sort of amazing when you think of it, right? It's amazing because it's very dry there. So let's take a quick look at a picture too. You can start with the first image maybe. Clouds, right? Everyone knows them. Cumulus clouds, I believe. Yeah, these are cumulus clouds. I remember my cloud types. Yeah, cumulus because they're convective so you can see they're bumpy on the top because there's fluid motions inside. Right. There's warm air rising up and cooling and all. The next image will show some, I think, an unusual shape, right? Clouds. Yeah, I thought this one was cute because it kind of looked like a dinosaur. A swan maybe, Hannah. Yeah. Just to make the point that oftentimes when we look at clouds, we're not thinking about the role they play in the environment. You're just looking at them as, oh, isn't that nice? All right. Yeah, okay. That's good. Yeah. And but clouds, we talked about, they are more dynamic, right? And maybe we've got time here to do a little quick little first video about the show sort of, not everyone has seen, right? Yeah. Going through a cloud, right? So this is from a... Yeah, this is a video, a time-lapse video as an aircraft is flying through a cloud or through clouds over a mountain in the Caribbean. And the little thing you see on the corner is actually a gust probe. It measures the three components of velocity. Sometimes you can see the clouds growing right in front of you. You see some rain going across the wind shield of the airplane. But I love this video because it shows how clouds are so dynamic. Right. Yeah. And we can see a little bit of that if you look up, for instance, over the ridge, the mountain ridge here on Oahu. Over time, you'll see the cloud pattern change. Sometimes there's very few clouds, no clouds. Other times, you can't see the tops of the mountains, right? They are shrouded. And then this, we see the downstream effects in terms of... I overlook the allo-like canal. Sometimes that canal is reasonably clean-looking. And other times it's basically chocolate brown. After those clouds have formed there and been pouring the water down. So this is great stuff because it really impacts how much water we have, right? And what we can do is a drought or a flood or anywhere in between. So this is then getting to be an increasingly critical area, right? Because as our climate is changing, the extreme events, extreme weather events are becoming more and more common, right? So we're getting more severe storms, more rain in shorter periods. I guess, what is it that I was reading recently? They say something like half of the rain in a given year falls on 12 days or something like that. And that's predicted now to be shrinking down to 11 days or 10 days within the next couple of decades. And that's, of course, that has impacts on everything, right? Because the more concentrated the rain is, the more rain is going to run off if you're not soaking. You're not going to get as good saturation of the soil. You're going to get more erosion. All these things that have impacts on us, right? Yeah, frequency is important. Rain rate is important. What we're referring to is if you have a low frequency, meaning just high rain rates during one period of time as opposed to lower rain rates, but more frequency is usually better for plants and animals because, like you said, it gives the land more time to soak it up and isn't as destructive. So we're going to dig more deeply into your work when we come back right now. We're going to have to take a quick break. Again, Allison Nugent is my guest. I'm Ethan Allen here on Likeable Science, and we'll be back in one minute. Hello, Chela. I'm here with... Cynthia Sinclair. And this is Trump Week. It's going to appear every Friday at 11 a.m. between Jay Fidel, Cynthia and myself. We talk about Trump, the activities and the news stories for that week as it pertains to the Trump administration. We hope you tune in and watch the fun. Aloha. See you then. Aloha. I'm Wendy Lowe, and I'm coming to you every other Tuesday at 2 o'clock. Live from Think Tech, Hawaii. And on our show, we talk about taking your health back. And what does that mean? It means mind, body, and soul. Anything you can do that makes your body healthier and happier is what we're going to be talking about. Whether it's spiritual health, mental health, fascia health, beautiful smile health, whatever it means, let's take healthy back. Aloha. And you're back here on Likeable Science. Your host, Ethan Allen, here on Think Tech, Hawaii. Dr. Allison Nugent is from UH Manoa, Southwest Department of Atmospheric Sciences, is with me today. And we're talking about clouds here. Great stuff. Maybe before we jump into this, we can take a quick look at our next video. We were talking about how clouds are dynamic, right, and the video here shows over. Well, tell us here. Yeah, this is a time-lapse video over about half an hour. This is actually the view from my office at UH Manoa. And you can see the clouds are growing and evolving, but they're not really moving. They're not... They're not shifting. They're not shifting. They look like they're going to come towards you, but then they don't. And this is all related to orographic precipitation. Right, because the air is going up, not towards you, basically. Orographic effects. So you have air rising on the windward side. This is taken from the lee side on the UH Manoa campus. And you have air descending there. But even though the clouds are trying to move upwards, overall, you have downward-moving air, which kind of kills the clouds before they were able to make it to the lee side. Okay, true. Yeah. Very interesting. Okay, but let's talk a little bit about some of your specific projects, things you're working on. So you were involved with a project called Domex. Yeah, so Domex stands for the Dominica experiment. And actually, the video we saw, where you could see the aircraft dust probe flying through clouds, that was from the Domex Field Campaign. Okay. And sort of, what were you doing there? What was the sort of significance of this? Yeah, the purpose was to look at the physics behind orographic precipitation. Okay. I think if you live on any of the Hawaiian islands, you know that there's a wet side and a dry side. But you may not know the details of what happens up in the clouds. Okay. And honestly, some of it is still an open question for scientists as well. Oh, excellent, excellent. Because you use, on your website, you know, you used an expression talking about thermally-forced convection versus mechanically-forced convection. That, to me, didn't make any sense. I don't think air is being mechanically-forced. Okay, so imagine the trade winds are really strong one day. So the winds are moving over. They come in contact with the mountains. They're literally mechanically or physically pushed upwards by coming in contact with the island. Okay, so it's higher pressure behind them while we're just shoving them up. Yeah, just shoving them up. Okay. Versus it's just lifting because it's warm. Yeah, versus the other case, when the wind speed is low, the air has a lot of time to gain that heat from the island. The island surface is heated by the sun and that the land surface passes it on to the air. And so that air becomes warm, buoyant, and then it rises. So the two types of convection are actually pretty different and they depend on the strength of the trade wind speed. Okay, all right. I don't know if you've ever noticed that when there are weak winds, oftentimes Mililani or the center part of Oahu, is more likely to get thunderstorms. Whereas when the trade winds are strong, the windward side will be really wet, but the lee side will be really dry. All of that's related to these two different things. Whether or not the wind is in control of the lifting of the air or whether the heating from the island is in control. Okay. Excellent. And then there's a factor of sort of what's in the aerosols, which can be a little salt, out here probably a lot of it is little salt particles, right, that are blown up off the ocean, basically. All of lots of other things, because there are viruses and bacteria and bits of seaweed, I suspect. And everything else gets blown up, too. And a lot of that ends up from the wind rising to some altitude and then providing a condensation nucleus as you put it, right? Yeah. Yeah. So why is it that salt is of sort of special interest in this process? Yeah, I'm particularly interested in sea salt aerosols or tiny particulates of salt. And the reason is because it's been shown that if you have a cloud droplet with salt and a cloud droplet without salt and you lift them both, the one with salt in it will grow faster than the one without salt. Makes it more likely to eventually be in a cloud? Which makes it more likely to eventually become a raindrop if it can grow large enough. So there's no distinguish between a cloud droplet and a raindrop. It's just a raindrop falls and a cloud drop is small enough that it remains suspended. So if this cloud droplet can get big enough so that it can fall, then sea salt could be important for creating rain. And that's a big open question in the field. The question of how you get a million cloud droplets to come together in warm rain to make a raindrop is a big open question. I say warm rain because the ice phase one, once you have really tall clouds where there's ice particles, that's a whole different thing. Whereas the question of warm rain when no ice processes are involved, it's either because there's turbulence. You have cloud droplets hitting each other and combining until eventually they're large enough to fall as a raindrop or it could be because of things like sea salt aerosols that allows these cloud droplets to grow faster than other ones. They grow faster because the salt is so-called hydroscopic, right? It wants to draw water into it. Yeah, it wants to draw water in. It also affects the surface tension of the droplet. You know how water has that meniscus in a cup? Imagine the same thing, but in a tiny little cloud droplet, it can affect how that surface tension holds to that. The salty water has less surface tension? I always get this confused. So if you're trying to boil an egg and you want it to cook at a higher temperature, you put salt in it, which means that salt increases the surface. That's true. I can usually figure it out. I just have to go through those steps. This shows how science ties all these different things together, chemistry, physics. This is really wonderful. Absolutely, and you don't have to memorize it because all of these things are things that we know in our daily lives. We just don't usually apply it to cloud droplet. Right, right. This is so intriguing. I had no idea that the clouds had so much unknown about us. Clouds have been around people, studied them forever. They know all about them. If everything was known, then the poor weather people wouldn't get... It is interesting. Beyond the fairly limited time frame, right? And some of it could be because of things like this. If we don't know exactly what it takes to get a cloud droplet to turn into a raindrop or how long or what things affect it, how are you going to be able to predict that a week out? Exactly. There's so many unknowns, and that's why we can't predict things exactly. So real quick here, you also study something that you talk about, like gravity waves on your website. Gravity waves is being sort of an astronomical, cosmological phenomenon. But are you using the term in that same way? Gravity... No. So you're referring to gravity waves meaning fluctuations in actual gravity. Whereas in my field, gravity waves means where gravity is the restoring force. So just like an ocean wave, gravity is the restoring force. I'm trying to flatten it back down. It's the same thing, but in the atmosphere you have a difference between upward motion and gravity being the restoring force of waves. So what you're referring to is I was involved in another aircraft field campaign down in New Zealand, and actually the local name for New Zealand is Land of the Long White Cloud in their language, and it's because there's an orographic cloud always over the ridge line and also upwards in the atmosphere there's wave fluctuations that you can measure 70, 80 kilometers high in the atmosphere because of this mountain on the ground. And so that was a really neat, dynamical project where we went and flew at about 12 kilometers height with lidars that looked upwards into the atmosphere up to the 70, 80 kilometer height and could see these fluctuations in gravity waves or waves where the restoring force is gravity. Interesting, intriguing. You never knew that mountains had so much of an impact on the atmosphere. That's intriguing that they're literally having impact miles and miles and miles above themselves and you've got your gravity trying to sort of stabilize everything back down as it were. That's amazing stuff. Where do you see this research going? Well, just like we talked about we hope that understanding better how clouds and how rain forms will help to make predictions of weather better or predictions of climate better if we don't know you know each one of these things it may be nothing or it may be everything and in models we use parameterizations or estimates to approximate processes and if you're not sure how it works those can lead to errors that propagate into the wrong weather forecast for next week and so a lot of the work that I do is very fundamental you know it's not going to change your life tomorrow but hopefully it will lead to these progressive step-by-step improvements in understanding the world around us. Excellent. Well thank you so much for being here Alice and this was even more enlightening than my usual guests you really expanded my horizons I had up in the clouds thank you so much for having me it was a pleasure and I look forward to maybe getting back some time we can dig more deeply into clouds. Of course yes, we've barely touched on the surface, we can go further. Exactly, exactly. I hope you'll come back and join us next week on another episode of likeable science here on Think Tech Hawaii. Till then.