November 17, 2020
EP. 188 — How Can We Get To Cloud Nine? with Kristen Rasmussen
This week on Getting Curious, we’re getting the down low on what’s up in the sky with Professor Kristen Rasmussen, an Assistant Professor of Atmospheric Science at Colorado State University and an expert on clouds. She and Jonathan break down cloud types, extreme weather, and the lasting impact that the 1996 movie Twister had on both of their lives—and one of their careers.
You can keep up with Professor Rasmussen on Twitter @KRasmusWx, and follow her research group at Colorado State University.
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188 — How Can We Get To Cloud Nine? with Kristen Rasmussen
Getting Curious with Jonathan Van Ness
& Kristen Rasmussen
JVN [00:00:00] Welcome to Getting Curious. I’m Jonathan Van Ness and every week I sit down for a 40 minute conversation with a brilliant expert to learn all about something that makes me curious. On today’s episode, I’m joined by the Assistant Professor of Atmospheric Science at Colorado State University Kristen Rasmussen, where I ask her: How Can We Get To Cloud Nine? Welcome to “Getting Curious.” This is Jonathan Van Ness. I’m so excited to welcome this week’s guest. She is an Assistant Professor of Atmospheric Science at Colorado State University, Professor Kristen Rasmussen. How are you, Kristen?
KRISTEN RASMUSSEN [00:00:36] Hi, Jonathan. I’m doing great.
JVN [00:00:38] Can it? Wait. I should say Professor Rasmussen because you have worked hard for this title. What do you prefer?
KRISTEN RASMUSSEN [00:00:46] Kristen is great. Yeah.
JVN [00:00:48] OK. So OK, I guess I do have a lot more, like, hard hitting, like, cloud and journalistic questions later. Not literally hard hitting, I say it, like, jokingly, but I have to start with a literal joke, first question, because this is why I’m obsessed with clouds. After you saw “Twister,” have you ever been the same since?
KRISTEN RASMUSSEN [00:01:10] I think that I am actually an atmospheric scientist because of “Twister.” I was in the sixth grade when I saw it. And that’s a very impressionable time in, in, in someone’s growth. And I saw “Twister” and I actually saw a tornado in sixth grade. I grew up in Boulder, Colorado, it was very rare. And I looked out the window and I saw a tornado and I was hooked. So for me, “Twister” was a life-changing movie. It changed my perspective of, you know, strong, positive women role models in the field, doing fieldwork, throwing instruments and crazy weather conditions. And that’s kind of, I think it launched my interest in the career I’m in.
JVN [00:01:45] Can I just say I have never started with, like, the million dollar question. It was an accident. But I also have been permanently changed from this movie. I was, like, I remember, I think I was in the fourth grade the year that it came out and it was on, it was in the movie theaters for a really long time, and I literally learned where the emergency exits in the movie theater were so that I could, like, put a rock in there. Like when I left the last time with my parents, I, like, left this, like, rock there so I could, like, put it in the door, like sneak back in because there wasn’t an alarm. ‘Cause I went, ended up seeing like nine times. Like I was obsessed-.
KRISTEN RASMUSSEN [00:02:20] Wow.
JVN [00:02:20] With it in the theaters like, oh my God. So now you literally became an atmospheric scientist!
KRISTEN RASMUSSEN [00:02:27] I did. Yes. It’s been, it’s been a dream come true. I’ve been able to do things in the field that I never imagined possible. We do amazing research. We go into the field, we bring instruments to all over the world, we went to Argentina a couple of years ago, basically chasing storms and trying to understand how they work. It’s really an amazing career.
JVN [00:02:44] OK, so I didn’t mean to dive straight into “Twister,” but as long as we’re at it. So is there like, could there really be a Dorothy-esque sort of, like, machine? Like where you go, like drop off a little thing with those little balloon things or the little plastic, like, mini thingys? Like, in the movie?
KRISTEN RASMUSSEN [00:03:04] So, yeah. At the time, it was kind of a, kind of a concept that they came up with for the movie. But I’ve heard of actually in just recent years that some scientists are actually trying to put small sensors into, into storms, kind of like they did in “Twister.” So it’s kind of generated a lot of interest because many of my atmospheric science colleagues became interested, especially ones around my age, became interested in the field because of “Twister” and the excitement about severe weather. So there are efforts to do this, but it’s not that common. But I think that people are thinking about trying to do something like this for research purposes.
JVN [00:03:36] Amazing. Well, I’m glad that I’m not the only one that’s, like, super obsessed with that movie. So then the other thing was is like what really started this episode and why I was so curious about it was “Twister” at first. Then it was just like looking at clouds all the time because they’re so pretty and they’re all so different. And why are some some ways and why are some other ways? And also severe clouds and, like, so I just got questions coming out of my ears. But in order for us to even get there, like, what’s the basic tea on clouds that we need before we’re going to dive right in? Like there’s like eight kinds, there’s, like, the Cumulus, there’s the Nimbus. What else is there?
KRISTEN RASMUSSEN [00:04:16] Yeah. So Cumulus are kind of like those kind of popcorn, cotton ball like clouds that you see. They’re really pretty. You see them, you know, in the beach or kind of, you know, wherever you are. We also have clouds that look more, like, layers. Those are Stratus clouds. So they look more like layers. It’s kind of like if you’re, think about Seattle, where you have, you know, it’s kind of rainy, the whole sky is gray. Those are, like, layered Stratus clouds. There’s all kinds of clouds. There’s, there’s, you know, we, in our field, we have a glossary of clouds. There’s so many types. And that is one of the things that keeps us all really excited about studying clouds is that they’re so different, they’re so many types. They happen in different levels of the atmosphere. Where I live here in Colorado, we have really fascinating clouds that happen because of the waves that come off of the mountains. We get kind of Lenticular. They’re called Lenticular clouds. They look like, they kind of look like UFOs. And actually the first UFO sightings that happened in the 1950s actually were attributed to Lenticular clouds downstream of Mount Rainier in, in Washington state. So there, there’s some amazing variety of clouds in the world. And they, where they occur is basically determined by a lot of times topography, by land, by a lot of the moisture content and the air itself. So it’s a, it’s a fascinating field because there’s so much variety.
JVN [00:05:32] OK. I also remember, I think Cirrus clouds. Are those as a cloud?
KRISTEN RASMUSSEN [00:05:36] Yes. Yes. Cirrus clouds happen really high up in the atmosphere. They are composed primarily of ice crystals. So they have more of a streaky, we call them Mares’ Tails, sometimes, they kind of look like horse tails. They’re really streaky and kind of wispy.
JVN [00:05:50] Yes. Yes. Yes.
KRISTEN RASMUSSEN [00:05:51] Yes, they, yes. They look wispy because they’re primarily composed of ice crystals, whereas kind of like a Cumulus, popcorn types of clouds, those are composed mostly of liquid water drops. And so they look kind of more bubbly and that kind of thing. So the look of the cloud can also tell you about what’s inside.
JVN [00:06:07] I can’t believe Cirrus clouds are made of ice. So if you were in a plane like one of those like planes in the movies that like the pilots’, like, head is out, and like the person’s in the back, you know, because like they’re like, you know, like.
KRISTEN RASMUSSEN [00:06:20] Yeah. Yeah.
JVN [00:06:21] So if you drove through a Cirrus cloud in a plane, it would literally be little ice crystals.
KRISTEN RASMUSSEN [00:06:27] That’s correct. Yeah. You would, you would actually see little ice crystals. And there are actually research aircraft in atmospheric science where they put instruments on the outside of the plane. They fly through clouds and they collect particles or they take images of the particles. So you can see the different types of crystals, there’s, you know, long ones and short ones. You can also tell the sizes of the liquid drops if you fly through a lower cloud. So there’s all kinds of really exciting ways to understand what’s inside of the cloud.
JVN [00:06:51] OK, I have another question. So is there any difference between, I know you said atmosphere, but what about, like, Northern Hemisphere versus Southern Hemisphere? Does that change clouds?
KRISTEN RASMUSSEN [00:07:00] Yes. So. Well, we see similar types of clouds in the northern and the Southern Hemispheres, just based on kind of whether you’re near the tropics. So then you get near the poles, you get different types of clouds based on the temperature and a lot of the properties of the atmosphere.
JVN [00:07:13] Oh, my god, really?
KRISTEN RASMUSSEN [00:07:15] Yes. And so, but we do see similar types of clouds in the Southern Hemisphere as well. But some of the storms that I study, I study some of the deepest convective storms that happen on the entire planet, they occur in subtropical South America. So in, like, Argentina, Uruguay. This region is an incredibly productive region in terms of really deep severe weather, giant thunderstorms with hail and tornadoes and floods. And so, you know, studying how clouds vary across the globe is one of the ways we can learn about clouds in general. And that’s one of the things I’m passionate about.
JVN [00:07:48] Oh, my god. Question. What deepest? What? Deepest what what’s?
KRISTEN RASMUSSEN [00:07:53] So the deepest thunderstorms in the world. So they are the tallest thunderstorms, the taller the storm is and the more intense the storm is in terms of how deep it is in the atmosphere, the more likely it is to produce really large hail, heavy rainfall, tornadoes, severe weather. And so we look at the depth and the intensity of storms in order to understand, you know, where do we have the most intense severe weather. And so I actually do research using some of the first space-borne precipitation radar observations. So these are active sensors that are sending out pulses that take basically you can imagine this is like an MRI through a cloud. It’s looking at the full internal components of the cloud and we can tell how intense it is and how deep it is. Research from that satellite showed that South America has some of the most intense storms anywhere on the planet. And this was previously unknown before about 2006. And I spent my entire time when I started as a graduate student in 2007, all the way through now. And then I mentioned we actually went down there with giant radars and weather balloons and things like that a couple of years ago to study this really unique population of really intense storms.
JVN [00:08:56] OK, maybe I just misheard, but I feel like when you said, like, deepest something something I feel like, there’s, like, a ten dollar science word that I hadn’t heard before, like the world’s deepest something storms, or did you say like just like deep severe weather? Maybe that was what it was.
KRISTEN RASMUSSEN [00:09:10] I may have said, I may have the convective thunderstorms.
JVN [00:09:11] Yes, convective.
KRISTEN RASMUSSEN [00:09:11] Yes. Yes. So-.
JVN [00:09:14] So what is that?
KRISTEN RASMUSSEN [00:09:15] Yes. So convection is essentially if you imagine, if you have, you know, a warm-, an air mass that gets warm. So it gets warm and it’s, it’s absorbing solar inf-, energy. The warm air mass wants to rise up in the atmosphere. So that’s called convection. And so when we have really strong heating on the surface, we have really buoyant and kind of strong motions that go up in the atmosphere. This creates really vigorous updrafts, really strong clouds, and it supports things like tornadoes and hail formation and other severe weather producing phenomena. So we look for how deep these storms are in order to understand their potential for producing severe weather. And so South America, having some of the deepest storms indicates that this region has, you know, among the most, the world’s most severe weather impacts. And this is actually true. We have verified that, that this is likely the case.
JVN [00:10:02] So when you see deepest, that means like how thick the clouds are, like how vertically thick the clouds are?
KRISTEN RASMUSSEN [00:10:07] Exactly. Yes. So the cloud extends from, you know, something called the cloud base. Which is where the air masses, it rises up, it becomes saturated. Once it becomes saturated, further cooling causes the water vapor to condense into small water droplets. The small water droplets are basically what are composed of the clouds you see outside, unless they’re Cirrus, which are ice. Like we talked about. And the, as the air continues to rise, it creates more cloud. And the, the, the deeper the cloud is, the more space there is to produce large precipitation particles, hail, you know, the updrafts have to be really, really strong in order to become such a tall storm. And all of these things are connected to the intensity of the storm that that relates to us on the surface with severe weather impacts like hail and rain and flooding.
JVN [00:10:53] So once the cloud becomes saturated and it starts making the water droplets. Is that just what rain is then?
KRISTEN RASMUSSEN [00:11:03] So the cloud droplets are really small. What happens when you create rain is that these little cloud droplets start to collect together. So they run into each other in the updrafts and they start to create larger and larger particles. They start to rain out when they’re large enough to basically have enough mass to fall through the, any upward motion. So, and so they have to become large enough in order to fall to the, fall to the ground through the air mass that’s, that’s moving up in the atmosphere.
JVN [00:11:28] Because I feel like sometimes on road trips, like, you can see like the, like, the columns of rain coming, like, down below, like, the clouds, like, you can see, like, where it’s stopping and starting. So that’s just like where all the molecules were like running into each other a lot? And then-.
KRISTEN RASMUSSEN [00:11:42] Yeah-.
JVN [00:11:42] What’s this updraft deal? What’s the deal with the updraft?
KRISTEN RASMUSSEN [00:11:45] So updrafts, it’s representing, so that convection topic that I just talked about. So when you have heating of the air mass, especially near the surface during the daytime, you know, the ground gets much hotter than the air. We have air masses that rise up in the air. And so the fa-, it’s basically the speed of how fast the air is moving up in the atmosphere, we call these updrafts. And so the stronger the updraft you have, the more likely you are to have a really vigorous thunderstorm. So things like supercell thunderstorms that are known for creating tornadoes, especially in the United States. These have some of those strongest and most vigorous and also wide updrafts that we see. They’re really strong, they’re really robust, and they can loft a lot of air and produce really vigorous motions that produce lots of collisions of particles to create large drops, also hail. And they also can produce very strong things like tornadoes as well. So, so we rate the strength of that upward motion and understand how severe the storm might become.
JVN [00:12:42] How do you rate that?
KRISTEN RASMUSSEN [00:12:44] So the way that we do this is we use, we typically use instruments called “radars.” So these are basically active sensors. You’ve probably seen some, you know, the National Weather Service in the U.S. has, they’re scattered all over the U.S., which is great. It’s an active pulse, we send out a pulse. And what happens is that pulse is reflected off of all the particles in the cloud. And we actually measure what comes back to the radar. So we admit a pulse and then we measure what is reflected back to the radar. And if we have really large particles, and especially if we have large, large concentrations of particles in the, in the cloud, we get a really big reflection. And so we get really high, you know, kind of reflection.
JVN [00:13:20] Is that Doppler?
KRISTEN RASMUSSEN [00:13:21] It’s a Doppler radar. The Doppler radar, we send out two pulses and we can tell how it’s moving. So we send one and we get that information back, we send out a second one and we compare the time and where things have moved since the first gate, since the first pulse. And we can see, OK, is it moving away from us, is it moving toward us. And that’s the way we can see little rotations with tornadoes. We can see where the storms are moving. So it’s a really fantastic tool that we have available to us in the U.S. And that’s the way that we’d really diagnose the severity of these weather systems.
JVN [00:13:52] That makes so much sense. So on the Weather Channel, when they say about that horseshoe in the Doppler, like, the all-dreaded horseshoe. Really, that’s because, like, that’s, like, swirling. So, like, that’s just showing like the beginning of the storm, like swirling?
KRISTEN RASMUSSEN [00:14:06] Exactly. Yeah. You’re seeing that kind of couplet. The rotation couplet. And so it’s one way that you can kind of tell that there’s a turn, like really rapid rotation in the, you know, in the storm that might indicate the presence of a tornado.
JVN [00:14:19] Oh, my god, oh, my god. OK. So what type of clouds are the thunderstorms?
KRISTEN RASMUSSEN [00:14:25] Yes. So those are called Cumulonimbus clouds. So Cumulus clouds can be anywhere from really small popcorn, little clouds all the way through really vigorous giant thunderstorms that extend from the cloud base. So where the air becomes saturated, all the way up to the tropopause, so that’s the top of the bottom layer of the atmosphere. These are some of those really deep giant thunderstorms that we talked about that, that happen in South America. The Nimbus part of the Cumulonimbus word actually means “rain.” So this means a giant Cumulus cloud that also is producing rain. So that’s, it all, all of the cloud, the cloud names actually come from Latin, Latin prefixes. And so Nimbus means, means “rain.”
JVN [00:15:06] So what differentiates a Cumulonimbus, like, thunderstorm cloud from just like a Cumulus cloud? “That’s just like a happy little like, that one looks like, you know, a dog. That one looks like a whatever,” you know?
KRISTEN RASMUSSEN [00:15:20] So the difference is, is really the fact that the Cumulonimbus clouds have to have enough vertical development in order to have lots of particle collisions, to create large enough raindrops to fall out and produce rainfall. So when you have a Cumulus cloud that is producing rainfall that, that we would call a Cumulonimbus and that term has actually specifically reserved for thunderstorms. So really intense thunderstorms that are really very, very tall storms. They tend to have really strong updrafts and also produce lots of rainfall.
JVN [00:15:50] OK, so I’ve heard that you have like, like a lot of these, like, really strong ones, the convection ones have happened in South America. Now. Due to my obsession of “Twister” in the 90s, I think I learned because of that, that, like, I’m, and I also grew up in, like, not to brag, but I did grow up in Tornado Alley, honey, I have lived through-.
KRISTEN RASMUSSEN [00:16:08] Yes.
JVN [00:16:09] I lived through like an F2 in 90-something, like the front of our swim club got blown off, honey. It was major. It was amazing. And then after, like, we all came out of the basements, we just like walked all around the neighborhood with, like, the local TV news crews and, like, acted really shocked because we were just like, oh, my God, it’s just like “Twister.” No one died and, like, everything was OK. So thank God. But we were just, like, oh, my God. Like the broken glass. We couldn’t believe it. It was amazing. Because, like, no one was hurt. But there was like just enough to like, oh, my God. So I learned at that time, like, you know, how like in the middle of, like, like, yeah. For all of America, like North America, like the weather goes from, like, west to east and then like isn’t like all through the globe, like doesn’t it go, like, different like west to east and east to west. Like based on your, like, how, right?
KRISTEN RASMUSSEN [00:16:59] It does. Yeah. That’s actually right. Yes. So in, kind of, so where you’re talking about kind of in Tornado Alley and where we live in the U.S., a lot of our country is in the mid latitudes. So it’s kind of, we’re affected by the jet stream. So this is the large, kind of large jet stream that, that basically flows across the entire Northern Hemisphere that meanders, of course, it creates, you know, we get our weather patterns usually from the jet stream, but that’s a westerly flow. So it’s blowing from west to east. We have the same type of westerly jet stream in the Southern Hemisphere, actually, that affects South America. So the same jet stream that’s affecting the storms that we have in the Uni-, in the United States, is also present in South America. However, you are correct that in, in the tropics, the trade winds, so if you’ve been to like Hawaii or, you know, nice tropical islands, there’s always a pretty constant like 10 to 15 mile per hour type of wind. It’s usually coming from the easterly direction. So it’s winds blowing from east to west. Those are trade winds. And so that’s a very common tropical feature.
And so depending on where you are in the world, yes, you will experience different types of, of wind flows. And that does affect where you’re likely to get things like severe weather. My grandma was from Hawaii. And so if you ever been to Hawaii, they have a lot of wind sports, like wind surfing and kite surfing. The winds there are so predictable and always from the same direction that people who do wind sports love it because it’s, you know, exactly the direction it’s coming from. And you know the strength because it’s really predictable and a very constant feature of the climate. So, yeah.
JVN [00:18:28] OK. Fascinating. Now. Like. But so with, like, what’s the Tornado Alley area of like this, of South America then? Like with this, like Peru-.
KRISTEN RASMUSSEN [00:18:38] Yes.
JVN [00:18:38] Tell us all about, like this, like your studies. Yes, tell us all about it.
KRISTEN RASMUSSEN [00:18:44] Yes. OK. So connecting this to the United States, so the deepest convective, or the deepest thunderstorms on Earth occur in the vicinity or downstream of major mountain ranges. So in the U.S., we have the Rocky Mountains. This helps to kind of deflect flows. It brings a lot of moisture out from the Gulf of Mexico. And then we have our westerly flow coming from west to east over that region, basically providing a perfect environment for severe weather to form. In South America, we have a very similar setup. So if you imagine we have the giant Andes, the Andes are actually about double the average altitude of the Rockies. They’re really tall. It’s like a wall.
In South America, we actually have flow coming, low level flow coming down from the Amazon basin. The Amazon is thought of as a kind of an inland, kind of a green ocean. There’s lots of moisture. It’s bringing that moisture down into Argentina from the Amazon. And then we still have that westerly jet stream flow coming from west to east over the Andes. And so we have a very similar setup in terms of what we see in both continents. And so in Argentina, our, our Tornado Alley is actually displaced a little bit from the mountains, but it’s kind of in middle to eastern Argentina into Uruguay and southern Brazil. So they do see a lot of tornadoes in that region, just like we have a Tornado Alley here. And it’s a similar setup in both places.
JVN [00:20:03] And do they do like the F1 through F5 too? Like is that like everywhere or no?
KRISTEN RASMUSSEN [00:20:07] They do, yes. So that’s a pretty standard way to rate the damage of, of, of a tornado. And so they do use that. So when I’ve seen storm reports, although our storm reports in the United States, we have many, many more and a very nice archive. It’s a little bit different in South America. But the storm reports I have seen, they do rate the tornadoes based on the same scale that we see in the U.S.
JVN [00:20:30] OK, I feel like I have to ask. Do they twist the same way south of the hemisphere? They do, right?
KRISTEN RASMUSSEN [00:20:38] So that’s a really, that’s actually a very good question. I actually taught about this in my class the other day.
JVN [00:20:43] Really?
KRISTEN RASMUSSEN [00:20:45] So. Yes. So the effect of the rotation of the Earth only acts on really large scale flows. So really large, you know, atmospheric motions. When we get down to the scale of tornadoes, it actually does, the rotation of the Earth actually doesn’t have any effect on the actual rotation of the tornado. So we actually see tornadoes even in the U.S. that rotate both directions. We have a preferential rotation, but it’s not governed by the rotation of the Earth like what we see with really large scale, wea-, weather patterns.
JVN [00:21:15] Ok, well, this is going to bring up a lot more questions. ‘Cause don’t cyclones go the other-? Oh, my God, we have to take a break. We’re going to take a really quick break. We’ll be right back with more “Getting Curious” after this. Just so everyone knows, really quick, after, before we actually do literally take a break, because I don’t think we’ve ever explained this. But we do “Getting Curious” on a Zoom now, everyone listening, so we can see each other, Kristen and I. And then one of our producers holds up this little break sign, but no one ever knows that. And then whenever, like, I see that break, it’s really, I’m horrific at acting like it, you don’t see the break sign, and then I always audibly gasp. And so it’s fun if we leave that in this time because it’s just, you know, but we’re going to take a really quick break now. We’ll be right back with more “Getting Curious” after this. Welcome back to “Getting Curious.” This is Jonathan Van Ness. So we just left you on such a major aha moment. And we are very excited to learn more about this. But don’t cyclones go the other way, than hurricanes?
KRISTEN RASMUSSEN [00:22:10] So, so large scale cyclones, like, like tropical cyclones.
JVN [00:22:15] Oh, ’cause those are gigantic.
KRISTEN RASMUSSEN [00:22:16] They’re really big. Exactly. So they’re very large. And so they are affected by the rotation of the Earth. So you’re correct, the cyclones in the Northern Hemisphere, they rotate the opposite direction in the Southern Hemisphere because they’re large enough that they are affected by the rotation of the Earth. But once you get to kind of smaller scales, you know, like tornadoes and dust devils and things like that, even, you know, I’ve seen some YouTube videos of people showing their toilets spinning the other way in the Southern Hemisphere. That doesn’t, that’s actually not scientifically correct. That actually, those scales are not affected by being in the Northern or the Southern Hemispheres.
JVN [00:22:49] OK, can I just say that is, I was, when I went to Japan and Australia for the first time, I was kind of devastated that the water didn’t go the other way.
KRISTEN RASMUSSEN [00:22:59] Yes, I’ve heard that actually a lot from, from people when I talked to people about that. People actually look. But, yeah, just know that, you know, for, for large scales of the atmosphere, for under-, you know, for, for feeling the effects of rotation, you really need to be kind of on the scale like 2,000 kilometers or bigger. In terms of horizontal scales. And so those are really big systems that, that experience the rotation of the Earth.
JVN [00:23:20] OK. That’s so fascinating. I can’t stand it. So back to tornadoes. You said there’s some go left and some go right? Like, some twists both ways. And then you also said there’s a preferential trea-, so which way is preferred?
KRISTEN RASMUSSEN [00:23:34] So it depends on the, it depends on the, the, the wind shear. So wind shear is something, so it basically changes in wind, speed and direction with height. And so the wind shear actually provides spin in the atmosphere and that’s what actually creates the tornado when you tilt that, that shear up into the vertical. That’s a lot of details there, but it’s really the, the direction of the wind shear that determines what types of directions you can see with spin. And so in the Southern Hemisphere, we actually do see kind of the opposite frame work in terms of wind shear. So we do see kind of tornadoes that rotate in different directions. But like I said, and even in the Northern Hemisphere, we see both cyclonic clockwise and counterclockwise rotation in tornadoes.
JVN [00:24:24] So are they tor-, because, so basically, was the other piece of like the South American Tornado Alley, like, they’re like, they just don’t, there’s not like one country to like monitor the, like the severe weather. And so there’s not as clear of a record because it’s between, like, Uruguay and Brazil and Argentina?
KRISTEN RASMUSSEN [00:24:46] Yeah. So they, they do have some records of these events going back into the past. The issue, actually, is that Argentina just installed their first national radar network in 2015. So this was a very recent installation. This, and these radars are what we use, kind of we have a very extensive network in the U.S. In South America, they didn’t have this, this network, especially in Argentina, which is where we get these really, some of the most intense storms. And so it was really, the satellite based radar that showed that these storms are, some of the most deep and intense storms that helped convince the country to actually implement their own network. Because in terms of, you know, now casting and like predicting severe weather impacts for locals, if you have a radar, you know where it’s coming. You know, if it’s a storm coming and how intense it is. If you don’t have a radar, you’re basically blind.
I mean, you can see from the satellite, but you don’t know how intense or severe it is. And so for, for protection of life and property, installing this network has really changed the way that, that Argentina can operate with storm reports and warnings. So that was one of the reasons that this region didn’t have this information. But now they do have this network and we work with our scientists in our field campaign and we’re, you know, and they are, you know, becoming really, you know, advanced in sending text messages through cell phones and things like that for severe weather alerts to save, you know, property and life, which is really fantastic.
JVN [00:26:06] So you finished school in 2007 and then you went to South America, kind of brought a lot of, like, that is, so you saw like a space and an area that needed help in this, like, predictive forecasting area for severe weather.
KRISTEN RASMUSSEN [00:26:24] Yes. That’s right. I used the satellite radar data to, during my PhD to really understand, you know, why do the storms occur there? Why are they so intense? The answer is because of the Andes. The Andes produce a really severe environment that creates a really perfect environment for creating severe weather. We study these storms from satellite radars. But, you know, we, the satellite only passes over a couple times per day. So we don’t have the full lifecycle of an entire system from beginning to end. And that’s why we really wanted to go down and bring our own instruments into the field. Do a research project. And so that’s what we did.
In 2018, we had a project called Relámpago. Relámpago actually means “lightning” in both Portuguese and Spanish. So we fit the acronym to the word, which is sometimes done. We’ve brought radars, we had mobile radars where we were driving them around and placing them in good places. We had weather balloons, teams of students launching balloons, taking all types of weather observations. We had lightning observations. We had streamflow measurements, all kinds of things. And we were able to see the storms from beginning to end. And this has changed the way we can see the whole convective storm life cycle process. And that’s something that we’re currently doing research on now.
JVN [00:27:30] Oh, my God. Tell me about it. Whatever you can tell. So, but then a national one got installed in 2015. So did that kind of help, like, having that foundation?
KRISTEN RASMUSSEN [00:27:40] It did. Yes. We were able to look at, you know, some of the early data from that network and start to connect the pieces. So the nice thing with our research radars is we can actually go in and in real time, I’m changing the way that the radar is scanning. So I see a storm coming in to the, to the radar domain. And I say, OK, I want to scan this storm in a very particular way to meet my research objective. You can’t do that normally with these operational radars. But yes, the network has greatly helped understanding how these storms evolve in this region.
Summarizing the field campaign, it was an absolutely incredible opportunity and experience. I had studied these storms for basically 10 years, remotely, from a satellite, before I actually went down into Argentina and saw them with my own eyes. It was an unbelievable experience. I remember seeing the thunderstorms for the first time and just being like, wow, this is so exciting because I’ve studied these storms and they are some of the most intense ever, you know, on the planet, except I haven’t actually seen them with my own eyes. And that’s the intuition, that when we go into the field, it’s really important that we can see the things we study and we can understand, you know, some more about them just by using our, our eyes.
JVN [00:28:43] So what were you surprised by? Being there in real life–
KRISTEN RASMUSSEN [00:28:47] Yeah, I think one of the things that we were most surprised by was the variability in a lot of the features we had to kind of looked at from, you know, from the previous research. So there’s something called the “Low Level Jet” that’s bringing moisture down from the Amazon that I mentioned previously. This jet feature is really, it’s really important in the convective development perspective, but it is actually pretty variable. So the strength and how, how often it’s there and what it looks like in the depth of the atmosphere. This is a really, thing, important thing that we were able to see because we had very rapid launches of, of weather balloons to sample the full profile of the atmosphere and the winds. We also were really impressed by the fact that these storms are, you know, we, we were seeing that they are, you know, really intense.
They are, they do happen very frequently and they happen basically right against the foothills of the mountains. They, they are initiating along the topography. The topography helps to lift the air a little bit higher and gives it a little bit of oomph to go, you know, for these updrafts. And so we were seeing this happening on a daily basis. These systems were really connected to the topography. And that was a hypothesis that I had based on the satellite radar data, but it was really great to go in the field and confirm that, yes, we are seeing this, but we are seeing lots of other very intricate, detailed processes that are happening with the topography and the convective storms that are, that are happening in the region. So it’s very exciting and we’re in active research mode right now, trying to understand what we saw in the field.
JVN [00:30:07] Is there any difference because, like, Tornado Alley in North America is, like, kind of plains-ish, and that area isn’t-? Or is that kind of below the Amazon or is it not around it?
KRISTEN RASMUSSEN [00:30:18] Yeah. So it’s, so it’s south of the Amazon and it is actually fairly, you know, it’s kind of like cornfields.
JVN [00:30:25] Oh.
KRISTEN RASMUSSEN [00:30:25] You know, they have soy, and so they have similar types of crops to what we have in kind of the Great Plains of the US in Tornado Alley. So the mountains are on the, on the west side. But then as you go to the east, it’s just basically flat. So it’s very similar in terms of the setup to the United States, except that the Andes are much taller. It’s a much taller mountain barrier. And we think that the, the actual the height of the Andes creates an environment that, that drives these more severe storms in, in lee.
JVN [00:30:53] That’s fascinating. I can’t get over how fascinating that is. So remember how you were telling us out the wall clouds earlier? Or like the layered, like the clouds that-.
KRISTEN RASMUSSEN [00:31:05] Oh, yes, yes.
JVN [00:31:07] Do those ever create, like, severe thunderstorms or is it always the cu-, because I feel like those wall ones look kind of scary sometimes?
KRISTEN RASMUSSEN [00:31:14] Some of those, kind of like the flat, layor-y, the Stratus clouds.
JVN [00:31:15] Yeah.
KRISTEN RASMUSSEN [00:31:16] So typically Stratus clouds are in environments that we call, they’re more stable environments. So they tend to not be as, you know, as productive of kind of convective thunderstorms. We do see some, you know, for example, you know, at the upper parts of thunderstorms, you actually have a flat cloud at the top. We call this an Anvil cloud. It’s primarily composed of that wispy ice Cirrus at the top. Because it’s really strong winds at the top and it’s blowing all the particles around. But typically with Stratus clouds, we typically do not expect to see severe weather impacts. You can see rain and things like that from Stratus clouds, but you won’t see tornadoes and hail and things like that from, from Stratus clouds. So Cumulus clouds are really the ones to be watching for if you’re interested in severe weather.
JVN [00:32:00] So what about the types of storms? There’s like, is there, do you categorize storms in different ways?
KRISTEN RASMUSSEN [00:32:07] We do, yes. So one of the things that I do in my research actually is looking across the globe at these satellite radar observations and categorizing them into different types. So we, we use a, there’s, you know, individual thunderstorms, if you think of, kind of, like, heating from the surface, it’s creating this individual cloud that, you know, you can kind of see this with your own eye. It looks like a, you know, a kind of a cellular cloud. We call these kind of discrete or individual thunderstorms. So these are kind of, there’s just kind of one updraft. It’s kind of its own cell. There’s also something that is something that I really am interested in and something we’re really working on studying in Argentina is something called mesoscale convective systems. These are when we have individual cells that start merging together into these giant complexes of storms. They’re very large. They, they develop their own kind of a flow through the storms and they can reinforce a lot of emotions. A lot of these are producing things like really strong winds. You may have heard of things like “bow echos” or “squall lines.” These types of storms are very-.
JVN [00:33:05] Squall line! I’ve heard of squall line.
KRISTEN RASMUSSEN [00:33:08] Yes, it’s basically a very thi-, a line of very intense, you know, convective updrafts that are all aligned along the same direction. And they can be, you know, the definition is actually that they need to be 100 kilometers in, you know, in the horizontal direction in any kind of given direction. So they’re actually quite large systems. We see a lot of these in the central United States. If anybody lives in kind of the Tornado Alley region, if you ever have kind of really intense convective thunderstorms and rainfall in the middle of the night, these are typically associated with these giant mesoscale convective complexes that are coming across the U.S. as they are merging together and growing up into these really large systems, we see very frequent upscale growth. We call this upscale growth or convective organization in South America as well. And so that was one of the primary goals of our Relámpago field campaign, was to observe the convective organization process from beginning to end. So we start with, you know, daytime heating of the surface.
We have individual cells that are basically coming up and forming because of the heating. Those cells begin to merge together. And at some point, basically they maximize at midnight, they turn into these giant complexes that cause, they’re, they’re well known for causing flooding and really strong winds. Sometimes they can also be associated with hail and occasionally tornadoes as well. So there are, there’s a whole spectrum of storm types. And so we try to categorize them in these ways. But in terms of the convective storms, this is kind of one of the things we do. There’s also tropical cyclones. There’s, you know, there’s all kinds of other clouds. We have large extra tropical cyclones. These are kind of our winter storms. You know, associated with a really large scale weather patterns, there’s very specific clouds and storms that are associated with, with those types of structures as well. So that is something that we are working on doing. And it’s, it’s a really active part of our research is categorizing the types of weather that we see.
JVN [00:34:51] What are some of the different convective thunderstorm type categorizations that we’re getting or doing? Is it, like, little bit, big ass one, like, like eastern shear storm? Like what are you, how are you doing it?
KRISTEN RASMUSSEN [00:35:07] Yeah. So one of the cat-, so in the, in the convective storm categories, these are basically like your Cumulus types of clouds. We have one where we call, it’s a shallow, isolated cloud. So we restrict it to be under five kilometers in depth. So it’s a really shallow, very small type of system. We see these kind of in the maritime regions, you know, if you’re sitting on the beach in, in Hawaii, you look out, you see these little tiny popcorns. Those are the types of clouds we’re trying to identify with that category. We also calls, have a category called “Deep Convective Thunderstorms.” This is basically where we look at the intensity using radar observations, how, how high a very intense echo reaches in the atmosphere. And so we actually can tell how intense the storm is by how high up this very intense value of reflectivity is in the atmosphere. And so we try to categorize them based on their intensity.
JVN [00:35:54] What’s that bow echo that you were saying earlier? What’s that do?
KRISTEN RASMUSSEN [00:35:58] Yeah, a bow echo is, is in kind of the Mesoscale Convective System category, where it’s basically it’s got kind of a bow shape. If you think o, like, a bow and arrow.
JVN [00:36:05] Oh yeah, the squall line, yeah.
KRISTEN RASMUSSEN [00:36:07] Uh huh, exactly.
JVN [00:36:07] Yes.
KRISTEN RASMUSSEN [00:36:09] It’s a type of squall, you know, it’s, it’s in that, it’s a subset of a squall line. But it’s usually, there’s, like, a convective line that’s very well-defined at the front that’s rushing forward. And then behind it, you actually have stratiform precipitations. You have things like, more like Stratus types of clouds, more layered clouds behind it. And so these structures are very, very common in, especially kind of in the Midwest, in Tornado Alley regions, in kind of the late spring summer time frame. So you’ll see these giant complexes moving through. And that’s kind of, yeah. So those are the bow echoes.
JVN [00:36:44] OK. Fascinating. And we, we do see that sort of, is it the same time of year that we see that in the South American part too? Or is it a different time of year?
KRISTEN RASMUSSEN [00:36:51] It is. It’s just their spring and summer in the Southern Hemisphere. So, yeah, it’s the same, same idea. It’s, the reason is it’s when the cold air from the, from the Arctic is mashing up with the tropical air.
JVN [00:36:04] Oh.
KRISTEN RASMUSSEN [00:36:04] That happens a lot in the spring and the summer. And so when that happens, this is a great time for severe weather to occur in both hemispheres.
JVN [00:37:11] So within the active times. I guess. I wrote down a couple of times like “Why?” Like, why, is there some days when, as the heat builds up in, like, this singular cell, like, clouds come up and then they form together and they become like the bigger squall line? Is there sometimes where it seems hot and humid, but then it just doesn’t really develop? And then other days, it’s, like, a massive tornado and a massive flood like do we? Is that? I mean, I guess that’s obviously the point to like protect people’s lives, like in “Twister.” But, and property too, but more lives. But-.
KRISTEN RASMUSSEN [00:37:42] Yeah.
JVN [00:37:43] And cows. But why does it trigger sometimes so much worse than other times? What have we learned? Well, what have you learned?
KRISTEN RASMUSSEN [00:37:51] Yeah, that’s a great. That’s a great question. So there’s been a lot of work in the U.S. looking at kind of the, the connection between the warm air mass and the colder air mass that are coming down from the north and the warmer air masses coming up from the south. Where these air masses meet is a really great place to expect severe weather. However, I also told you that in the deepest convective storms, the most intense thunderstorms that we see on the Earth happened near major mountain ranges. And so what happens is that, let’s, let’s take the North America example here. What happens is in that kind of displaced spring and summer, we have a low level flow or a wind that comes from the Gulf of Mexico. This is bringing a really juicy, moist, warm air from the Gulf of Mexico up into Texas and in through the Midwest and Tornado Alley, the same time we have flow coming up and over the Rockies. So that westerly jetstream flows coming up and over the Rockies, and what this does is that flow is actually drier.
So it’s basically providing a capping inversion. We call this a cap. The way to think about this is if you have a soda bottle, right? And you have, and you put a cap on it and you shake it up. What you’re doing is you’re basically, you’re not allowing that warm and moist air that really wants to rise up in the atmosphere. You’re you’re placing a barrier over it and it cannot rise when it wants to. And that instability and that energy is building and building and building until it can be released by various things. So in the US, we have, you know, various things that, that release that energy. And that’s when we get our really violent thunderstorms that produce tornadoes. So we as atmospheric scientists and meteorologists, we look for environments where we have these flow features that are kind of coinciding in the vertical. And also, when we have the buildup of energy, we have parameters that we can use to diagnose how much energy is available if a convective parcel could rise in the atmosphere, how much energy would it have? And we can directly compare that to how strong the vertical motion or the updraft would be. So we, we, for forecasting, that’s how we, that’s how we do that.
JVN [00:39:43] OK, we’re going to take a really quick break. Listen to these few commercials then we’re going to be right back with more Professor Kristen Rassmussen after this. Welcome back to “Getting Curious.” This is Jonathan Van Ness. I hope you remember what we’re talking about because I have a question. What? Like so you’re basically studying how much energy it would have if there was a storm that could pop up there? Right?
KRISTEN RASMUSSEN [00:40:11] Exactly. Yes, exactly. It’s basically potential energy.
JVN [00:40:14] So you’re studying predictability.
KRISTEN RASMUSSEN [00:40:16] Yep, exactly. Yeah. So if that storm could realize that energy, how severe might it become? And that’s something we can measure from a weather balloon. That’s why we launched so many weather balloons, is to really understand the vertical profile of the atmosphere. And we can calculate these parameters directly from data from weather balloons.
JVN [00:40:33] So how thick is like a really severe storm? Like how thick would the cloud be on this really severe one?
KRISTEN RASMUSSEN [00:40:40] So a lot of times severe storms go all the way from like the cloud base, all the way up to the top of the troposphere. So the troposphere is kind of the lowest layer of the atmosphere. It’s where all of our weather and our clouds and our rain and all of our kind of the things that we experience on the planet Earth are located. I think it’s about. I can’t. Well, I think of it in kilometers.
JVN [00:41:03] Yeah.
KRISTEN RASMUSSEN [00:41:04] If that makes sense. So thinking about, like, you know, like 10, 10 to 15 kilometers or so, sometimes getting up to 17 or 18 or 20 depending on where you are. It actually varies depending on if you’re in the tropics or the poles. So it’s a. Where that is varies. But, you know, a lot of times we can see storms. You know, for example, in Argentina, we see storms, that get to 20 kilometers in altitude above the surface of the Earth, which is extremely high and very, very deep. And so you can imagine, there’s a lot of space in that cloud to create, you know, to have lots of air motions to, to build large precipitation particles to have hail that’s growing in, in the column. And so there’s a lot of, a lot of space to do that vertically.
JVN [00:41:44] So essentially, like a tornado is like a rotating cloud that, what’s a funnel cloud? How does it work? What happens up in there? That it’s like I’m going to spit out a rotating arm of death?
KRISTEN RASMUSSEN [00:41:59] Yeah.
JVN [00:42:00] Like what happens in the cloud?
KRISTEN RASMUSSEN [00:42:01] So a funnel cloud, just, it’s actually just a, like a tornado that’s starting to form. That hasn’t yet reached the surface. So when it’s just kind of in the, in the air, we call that a funnel cloud. Once it reaches the surface, it’s called a tornado. Essentially what’s happening is that we have, I talked about wind shear. So this is changes in winds with, with height and with direction. So this is causing spin in the environment. So we’re basically having rotation in the environment. What happens when that horizontal spin in, intersects with something like a convective updraft, so we have very vigorous air moving up, it tilts that spin up into the vertical. And a lot of times by, by stretching that column, a lot of times it spins up much, much faster and can create a very, really strong rotation that we see with tornadoes. You can imagine something like, you know, an ice skater. So an ice skater, when they’re spinning around, they’ve got their arms out to start. They bring their arms in and they conserve angular momentum, and so because of that, they start to spin much faster when their arms come in, their center of mass is much closer to the center. It’s the same thing with tornadoes. We’re stretching that column, we’re, we’re shrinking it and it spins up really fast. And a lot of times that’s why we see our tornadoes that, that have these really vigorous rotations.
JVN [00:43:10] Sometimes when you see videos of tornadoes, it looks like they meet kind of like in the middle like it almost, like, comes from like, like, like from the ground up. You know? So that’s kind of what’s happening then, it sounds like.
KRISTEN RASMUSSEN [00:43:25] Yeah. So there is actually an active research debate on kind of if the tornadoes are coming from the ground up or from the top down. So there are some active research on that. But I think the, the, the research community agrees that it’s the, like the, the change of that horizontal rotation into the vertical direction that is really responsible for at least creating the spin that we need for the tornadoes. But you’re correct that actually, you know, there is actually a debate on whether it’s coming from the top or the bottom.
JVN [00:43:50] OK, so I went a little bit, OK. Horizontal spin turning vertical. So where is the horizontal spin happening? That’s just because. Oh, oh! Is that from the weather just coming from west to east. But then the warm air is coming up from the Gulf of Mexico. So.
KRISTEN RASMUSSEN [00:44:07] Yes.
JVN [00:44:08] Where is the-? So is the horizontal spinning, is that the warm air coming up from like the Gulf of Mexico?
KRISTEN RASMUSSEN [00:44:14] Some of it is. Yeah. So it’s, it’s basically just changes with winds as you go up in height. And so the, the low level jet bringing wind up and moisture from the Gulf of Mexico and then the upper level flow coming in a different direction, that’s creating a spin, that’s a change in direction and height.
JVN [00:44:30] Oh, yeah, yeah.
KRISTEN RASMUSSEN [00:44:31] So we’re looking at, so it’s basically that energy that’s creating a rotation in the environment. And then we’re taking that rotation and spi-, and basically tilting it up into the vertical along a convective updraft. And that’s a lot of times what creates the tornado itself.
JVN [00:44:46] OK, I also wrote down, like, the Himalayas, like, 18 times.
KRISTEN RASMUSSEN [00:44:49] Yes.
JVN [00:44:50] Because, what about them? Don’t they have some tall things? Is there like an accidental Tornado Alley over there that no one even knows about? Like next to Tibet or Nepal or something? And we need to get a radar over there because do they not have a radar?
KRISTEN RASMUSSEN [00:45:01] So that’s a fantastic question. So I’ve actually done some work looking at the northwestern indentation of the Himalayas, near Pakistan and northwestern India. There is actually a very strong convective hotspot that happens right there. There’s some very deep storms, lots of lightning, really very, you know, very tall Cumulonimbus types of clouds that happen in that region as well. And so, yes, the, when I talk about this kind of globally, the Andes, the Himalayas and the Rockies are the three places on Earth that spawned the largest and most intense thunderstorms on the planet. And yeah, I, I didn’t mean to exclude the Himalayas, but yes, the Himalayas create really, really strong storms as well.
JVN [00:45:38] You didn’t exclude them, Queen. I was just curious because there, I just remembered, I love geography. It’s, like, randomly, I don’t know, like, I mean, I just liked it in eighth grade. But anyway, keep going.
KRISTEN RASMUSSEN [00:45:48] Yes. Yes. And so I don’t think that they see as many of the kind of like a Tornado Alley like we do here in the U.S. they the way that the mountains are set up, you know, with the Himalayas being mostly an east-west barrier, create a slightly different kind of environment in terms of how these storms grow once they form. However, Bangladesh is a really fascinating location. They have tornadoes and very severe weather, really big hail. And it’s something that is not very well studied. And it’s actually something that’s on my list of research topics to look at because it’s a very understudied region. They have very severe weather and we don’t really understand fully why this is the case. And so, yes, near these big mountain ranges, we do expect to see these severe weather types of events. But depending on the, you know, the orientation, the geography and the flows, it’s all different. This makes, you know, this makes it really exciting to study different places around the world.
JVN [00:46:41] I need to remember where Bangladesh is. Yeah, where?
KRISTEN RASMUSSEN [00:46:45] Yes. It’s closer to kind of the, the eastern side of the Himalayas. It’s kind of east of the, on the eastern side of India. So it’s, it’s displaced from kind of where I originally talked about in the northwestern indentation near Pakistan and in northwestern India. But it is a well-known place that experiences very frequent severe weather that, you know, that deserves more study from, from our field.
JVN [00:47:11] And do they have like the west-east flow there too? Of the-?
KRISTEN RASMUSSEN [00:47:15] Yes, they do. Yes, they are, they experience the, the jet stream there as well. However, because of all the land masses and Europe and the mountains, the jet stream is actually significantly disrupted. And so it kind of meanders quite a bit and it moves around a lot. It. And so there are some impacts there. But yes, they do generally have the west-east flow as well.
JVN [00:47:35] So really right now they either can do satellite monitoring of clouds or radar based monitoring. But if you do radar like, you have to have it, like, you know, installed, like, in a network so that, like, lots of scientists can monitor where it is relative to, like, the ground that it’s covering.
KRISTEN RASMUSSEN [00:47:52] That’s right. Yeah, though the ground based radars cover up to about 150 kilometer radius around the instrument. So it’s a really nice platform and it gives us a ton of information, but they fairly, they’re fairly localized. So, like, in the U.S., you have to have a network of them to see storms moving over time. With satellites, though, it’s really exciting, like, with, like, geostationary satellites that sit over a specific spot and look at the clouds over time. You can really see the changes in time of these systems. But with these large types of satellites, they don’t actually see the internal components of the storms. And so the, the radars on satellites pass over just a couple times a day. But they do look at the full, you know, the full three-dimensional perspective of the storm. So we try to use a combination of all these tools and also models. We use mesoscale models to try to simulate the atmosphere and what, what the storms do to connect the pieces.
JVN [00:48:43] So when you look at all the data that you’ve been able to collect over your career and you look at, specifically, like, this strong thunderstorm data, and we had mentioned it before, like a little tiny bit. But what are, it’s really just like a geographic location that determines, like, if it turns into a tornado or not?
KRISTEN RASMUSSEN [00:49:02] Yes, that’s actually right. Yes. So we do see that, kind of the places where we expect to see the most vigorous severe weather happen because they’re near these major mountain ranges. So it’s geographically tied to large mountain ranges, large terrain features that cl-, that cause flows to flow in different directions. I’ve done some experiments actually with my research where I change the mountains. So I had, I did a really fun paper where I took the Andes and I reduced it by half. I just, you know, made it 50 percent of its height. And it completely changed the way that the convective storm population downstream of the Andes formed, simply by changing the mountains. And so, yeah, the geographical perspective is really important. And understanding the topography is also really important.
JVN [00:49:41] Okay, so my hometown, Quincy, is, like, on a bluff. And so one thing that they used to say to me growing up when I was so obsessed with “Twister” is, like, a lot of this severe weather would kind of balance off the bluff and, like, kind of go over Quincy and so a lot of the tornadoes would happen like right east of Quincy. And if we ever saw the weather coming back from the east, like go to your basement. And like any of the times, we’re like there was really severe weather. It was, like, coming back from the east because it had, like, you know, like the clouds had, like, come back from the east because it was making like a thing. But why is it that, like, all of this similar, but maybe for me ’cause I was like, you know, 10 and didn’t have, like, access to all of that data. But like, why is it sometimes like on July 10th, if all things seem equal, like, one storm produces like a horrific tornado and then another thunderstorm is just, like, rain, some thunder and like, doesn’t have the vertical or doesn’t have, doesn’t create a tornado? Like, it’s, I guess just like something in the atmosphere is just different that time, it wasn’t rolling as hard or wasn’t as differentiating of, like, cold air meeting, hot air or something?
KRISTEN RASMUSSEN [00:50:50] Yeah. I think it determines, you know, the threat of severe weather, a lot of times we look at the thermodynamic profile. So this is from the weather balloons. We’re looking at the warm air and the cold air kind of where they’re meeting and how, how they, how they interact. We diagnose, kind of, where, where we think and how active we think the environment will be based on that parameter that basically estimates the amount of available potential energy in the system. But you’re right that, you know, we could have the same value of potential energy and we could have a storm that produces a tornado and also a storm that doesn’t produce a tornado. And so that’s a very active area of research.
It’s actually very hard to know which individual storm is going to produce tornadoes. That’s some of, you know, very active research in the severe weather community, because if we could tell which storm was going to produce a tornado, we could provide much more accurate and more timely warnings to the population. It’s actually very, very hard to do that. We have really great tools and weather models that can tell us, you know, all the combinations of factors that come together that are likely to produce these severe weather events. But the individual systems or ce-, or storms that produce tornadoes, it’s really, really challenging to know exactly which ones are going to be the severe ones. And so that’s something that people do every day in terms of their, their research topic is to figure out why that, that difference occurs.
JVN [00:52:08] So, I mean, I feel like we can’t talk about clouds and severe weather without talking about global warming
KRISTEN RASMUSSEN [00:52:14] Oh yeah.
JVN [00:52:15] I always think about like the devil’s advocate way of, like, what, like, a Trump supporter would say to that. They’d be like, “Storms have been around forever. I bet there’s been big storms, you know, blowing down a dinosaur’s house.” Like we’re probably not whatever. But I’m, I don’t believe this. I’m very much a climate change believer. But I’m curious to hear from a scientist who is studying data and comparing data over long periods of time, and you also worked shoulder to shoulder, I’m guessing, with other scientists who have been doing it for a lot longer than you.
Obviously, you guys can’t see Kristen, but she is very much in our age. Well, you already said it, you were in the sixth grade when you saw “Twister.” So I’m just guessing like I mean, when I first started doing hair, I was doing hair with, like, some of my favorite hairdressers. There was like this one lady named Sue who was like 68. And some of her clients were, like, literally, like, 99 and 100. And, like, they’d been coming to her like on an every weekly basis for like 40 years and plus time. So what do like the other scientists in the community say and how can-? Just knowing like awful ridiculous climate change denying comments like can you speak to some of the ways in which you interact with climate change on a daily basis?
KRISTEN RASMUSSEN [00:53:26] Sure, yeah. So we are, in, in the science field, you know, the climate change is kind of just a fact that we all, you know, are onboard with. We’re seeing impacts of climate change already happening in our, in our world now. You know, we’ve broken lots of records for rainfall. We’ve had, you know, crazy, you know, tropical cyclones like, you know, Hurricane Harvey delivering an amazing amount of rain. We broken so many rainfall records in just the past five years that that’s actually something that I actually, I’m hoping to study is heavy rainfall production. But in terms of climate change, we’re actually making really exciting advances in terms of being able to understand clouds and climate change. So traditionally, climate, climate models are used to kind of understand how climate will change, kind of, you know, hundreds of years in the future and also in the past. Right? We can see what happened in the past and look in the future.
However, a lot of climate models have fairly, you know, big grids sizes. So they have, you know, like, you know, 100 km or so grid boxes where a lot of the clouds that I’ve been talking about today are much smaller than that 100 km grid size. So a lot of my colleagues and a lot of my collaborators, we’re actually working on very high-resolution simulations using climate change, climate models to drive our high-resolution models. So we can actually understand the processes of how clouds may change in, in an environment that has warmer temperatures and has more moisture.
So it’s, it’s, it’s very well known that when we have increasing greenhouse gases, we have warming temperatures. What happens when we have warmer temperatures is that the air mass actually can hold more water vapor. So we can actually have more water vapor in the air, which is directly related to our production of clouds. And so I’ve actually done a lot of detailed research on understanding how the clouds may look in a future climate, maybe 100 years in the future. And it’s revealed some really fascinating things that I can talk about with respect to even our discussion of severe weather environments, that we can learn something about how these, these clouds may change.
JVN [00:55:18] Tell us. How are they going to change?
KRISTEN RASMUSSEN [00:55:21] OK. So that, that environment, the, the energy available for storms that I was talking about. It’s basically, the terms that go into that equation are basically moisture and temperature, and that’s primarily what it is. We calculated this same index in the future, a hundred years in the future over the United States. And what we found was that the energy that was available for storms in the future is increasing by quite a bit. So we have more energy available for the storms to tap into. However, I also talked about the cap, right? The, the soda bottle with the cap on top. That, the strength of that cap is actually very important in understanding if we can get a storm or not. If the cap is too strong, the lid can’t come off and the storm actually may not form at all.
And so what we looked at is we’ve also looked at the strength of the capping inversion in the future. And we found that that also increased in strength. So we have more energy available for storms to tap into, but we also have more energy suppressing those storms in the future environment. What this leads to is the storms that can break out of that cap, that can kind of break out of the soda bottle, when they can realize that enhanced amount of energy, they become extremely intense. They’re way more severe than the ones we see in the current climate. But the weaker to moderate storms that we see in the current climate, those ones are preferentially suppressed. They don’t actually tend to occur as frequently in the future. So our population of storms is actually shifting more toward a severe weather type of environment. And we see more frequent severe weather, less frequent kind of weak to moderate storms. And this is very concerning for those of us living in places like Tornado Alley that, that experience these very strong storms right now, with a warming climate, we expect these storms to become more frequent and also more intense.
JVN [00:57:00] What about for agriculture? With just, like, making normal precipitation? Like, wouldn’t that have a bad effect on, like, growing vegetables and fruits and stuff?
KRISTEN RASMUSSEN [00:57:08] It would. Yes. So, you know, most of the precipitation that we see across the growing region of the U.S. comes from those weaker moderate types of systems. So we may see changing patterns of precipitation. How often the precipitation is falling, where it’s falling, the season, the growing season, things like that. These are all very concerning things. So if you’re, if you’re interested in agriculture and this is kind of like your livelihood or if you’re interested in kind of the hail, you know, impacts on, you know, on crops and things like that, this is very, an important issue and it’s a very concerning thing to be thinking about with respect to kind of mitigation of these, of these potential impacts.
JVN [00:57:44] One thing that I like to think about, especially this year, is this idea of activism and this idea, well, obviously, I’ve always been a fan of activism, but this idea that we all have a place where we can be active and we all have like a lane that we can become really into. And I think that science is such a cool place for folks to do that, because if you’re naturally into it and you’re naturally like, you know, driven by it and want to study it, you can effect so much change and there’s so much to get into. There’s just so much richness to immerse yourself in and to have a purpose and a drive, and that’s just so amazing. And I think one thing that I would love to just ask about is, how has your life been fulfilled by your relationship to science and specifically for women that are listening?
One of my favorite guests we ever got to interview was Dr. Edith Eger, and she’s a psychologist and this Holocaust survivor. And she’s just incredible. And one thing that she said is when she was, like, when someone suggested to her that she should get her doctorate, she was, like, “I’ll be 50.” And then her friend was like, “You’ll be 50 anyway, girl.” So, like, it’s never too late. Essentially was like what it means to, what I took from that story. So what would you say to someone who’s, like, “I think I might be really interested in ‘Twister’ and science and clouds too,” or it’s always been electricity or whatever the fuck I’m into. Maybe it’s not science and clouds, but I think I really want to get into it. What do you say to someone like that?
KRISTEN RASMUSSEN [00:59:17] I would say just follow that. Follow that down as long as you can. I mean, I think natural curiosity about our world is really, really fascinating. There are so many topics, especially with climate change and environmental kind of issues, with kind of all these types of things related to climate change and the impacts in different places around the world. This is a really exciting time to be in, in these types of fields. We’re talking to policymakers. We’re talking to people who do air, air pollution. We’ve had crazy wildfires here in Colorado. We think they’re likely, you know, wildfires are expected to become more frequent. And we are, we feel like we’re seeing that impact already. So there’s so many things we’re seeing in our day to day lives that are affected already by the changes in our climate.
And there’s, you know, we just have a kind of a future path where we have to understand what’s going to happen. We have to have changes and, you know, policy changes that have, you know, that prevents, you know, all of these greenhouse gases and things like that from being released so that we can stop, you know, the rising temperatures and things like that. So for people interested in science, I say, you know, for me, I am very fulfilled by thinking about the world and learning something new about what we’re, what we see in our world and also trying to help people and make changes. Right?
We want to go into places, like, you know, places where they have really severe weather and they don’t have a great warning system or they don’t understand how these systems move because their, their networks are, are not present. How we can help people and make, make a change, I think, is one of the things that motivates me. And I really love that atmospheric science is very tangible. Like, I can talk to you about clouds. We can look out the window and look at clouds and think about how they look in models and things like that. That’s one of the things I love talking about. And so I would just recommend to follow your passion and follow the interests and, you know, see where it leads you. There are so many interesting careers that are happening in the environmental and geosciences right now. And, you know, I’m always happy to talk to people if they want to contact me as well about, about those types of things.
JVN [01:00:07] Obsessed. And then I feel like we’ve gotten to the point in the conversation where it’s like, I can’t tell if I missed anything because I was thinking so much about Helen Hunt in “Twister” and clouds and severe weather, but if there’s something that we’ve missed or we should have talked about that like I just did not hit because I was, like, too fascinated with, like, “Twister” and picking your brain for this glorious hour that we’ve been chatting. But is there anything that you just be remiss if you didn’t mention in our interview time together? Or that I really should have asked about that I didn’t?
KRISTEN RASMUSSEN [01:01:38] Well, you know, I think that there’s a couple things, other types of things that I do in terms of research. We’re also looking at the impacts of flash flood-producing storms in a future climate. So we’re actually identifying specific storms that have produced flash floods in the current climate. And seeing how they would look if they were happening in a warmer and moister climate. That research has produced really fascinating results that show that we, we think that we’re getting really a lot heavier rainfall and more total rainfall in these flash flood-producing storms in the future climate that has implications for things like Hurricane Harvey and a lot of the really heavy producing storms that we have now.
Climate change is expected to basically increase those rain totals. And that’s very concerning for places, especially in the Mississippi River basin, where the infrastructure there is outdated. It’s 50 years outdated, it was built in the 1930s, it was, has a 50 year life cycle. And we’re well past that and we’re having incredible problems with levees breaking and with dams and issues all along the Mississippi Basin. We expect to see greater impacts in future floods as well.
I also am doing work on snow pack, so I live in Colorado. Snow is a really big topic here. A lot of people love skiing and snowboarding and we’re trying to understand how in the future climate, how the snow pack may change. Is a snow season changing? Is is the amount changing? How will climate change affect, you know, where we get snow? It’s, it’s warming as we go up. The snow is isolated to kind of the higher parts of the mountains. And so that’s another topic that I’m doing that, you know, is not related to kind of the warm season kind of convective storms that I’m, that I’m interested in. But I am interested in all types of clouds and precipitation that happen, especially near mountains. So I just wanted to mention that just to kind of bring that up.
JVN [01:03:08] So is this snow getting way less? Are we? Are we just all fucked up?
KRISTEN RASMUSSEN [01:03:14] So it’s kind of a mixed, mixed package. Mixed results. We actually are seeing that there’s more precipitation, but more of that precipitation that’s falling is rain compared to snow. Right? So it’s a little bit warmer in the environment. We’re also seeing that as you go up in altitude, you actually, you can see that the snow line is actually moving a little bit higher. However, you know, the key takeaway from one of our projects is that it looks like the season is shortening. So the, you know, when we get snow in the fall and when we kind of melt the snow out in the spring, it seems like that season is shortening. And so that’s important if you’re in the ski industry and things like that, to know these types of parameters and to be able to prepare. Right? So, you know, maybe you need to have more snow machines or something like that to, to kind of mitigate for the natural precipitation that, that’s changing. So, but there will still be snow to ski on and things like that. It just, it, it may look a little bit different in 100 years.
JVN [01:04:02] But essentially, as far as like the whole thing with, you know, that upper bottle lid. And then as our stuff becomes warmer and wetter, it’s, like, that doesn’t only apply to like more severe tornadoes and less medium rain, it also means like when we do have a flash flood, it’s like bigger and worse flash floods. It’s, like, all the storms become more severe and potentially farther apart. But when they do happen, more severe.
KRISTEN RASMUSSEN [01:04:28] That’s right. Yeah. It’s applying to a lot of the warm season storms. A lot of the floods are happening kind of in the warm season as well. So this is, you know, this is something we’re trying to connect and it’s really exciting. And actually, this is a very cutting edge part of our field is that we’re able to now look at these very significant impacts at very high resolution. Right? So much smaller scale. These are 4 kilometer horizontal resolution models. So I can resolve things like rivers and lakes. You know, like things like that that are of interest to people, you know, the Army Corp of Engineers or, or people that are actually interested in the, you know, specific geographic points of interest. We’re able to start looking at these local impacts, which is really important for stakeholders and for people with applications in snow or flooding or whatever it is. And so this is kind of really exciting.
JVN [01:05:11] Like if your house is on a lake?
KRISTEN RASMUSSEN [01:05:11] Yeah. Exactly.
JVN [01:05:12] Like if you live on a?
KRISTEN RASMUSSEN [01:05:13] We could start to try to see kind of what we, what we can see in this general area. And, you know, that kind of thing.
JVN [01:05:19] Like, is your house going to be underwater in 50 years?
KRISTEN RASMUSSEN [01:05:22] That’s, you know, that is something that I know people are looking at. There’s, there are a lot of sea level rise and kind of those types of models that are, that are trying to estimate those things. And we’re getting to higher and higher resolution. And so we’re able to look at these processes more specific and more localized. Which is very exciting in our, in our field.
JVN [01:05:39] Yes. Predictive technology. Yes. Oceanic realness. Professor Kristen Rasmussen, thank you so much for your time. I’m so grateful for you and for your work. And thank you for coming on “Getting Curious.”
KRISTEN RASMUSSEN [01:05:49] Thank you so much for having me. It’s been a pleasure.
JVN [01:05:51] You’ve been listening to Getting Curious with me, Jonathan Van Ness. My guest this week was Assistant Professor of Atmospheric Science at Colorado State University Kristen Rasmussen.
You’ll find links to her work in the episode description of whatever you’re listening to the show on.
Our theme music is “Freak” by Quiñ – thanks to her for letting us use it. If you enjoyed our show, introduce a friend – show them how to subscribe.
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Our editor is Andrew Carson and our transcriptionist is Cassi Jerkins.
Getting Curious is produced by me, Erica Getto, Emily Bossak, Chelsea Jacobson, and Colin Anderson.
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