Speaker 1: Technology, Tech Stuff from stuff either and welcome to Tech Stuff.
Speaker 1: I am your host Jonathan Strickland joining me in the
Speaker 1: studio today our friend Dylan. Hi. Dylan, Hi. We're not
Speaker 1: talking about photo editing today. We are not. No, We're
Speaker 1: we're talking. Uh, you know, let's do some small talk.
Speaker 1: How's the weather. Well today it is overcast and uh,
Speaker 1: I believe there's a thirty percent chance of rain. Yeah,
Speaker 1: it's a little breezy. We went up to the roof
Speaker 1: of the building and re enacted parts of Titanic. I
Speaker 1: spread my arms and Dylan held me and I said
Speaker 1: I was king of the world. They told me to
Speaker 1: go back downstairs. No, uh, we're talking about whether not
Speaker 1: because I like terrible small talk, although I'm adept at it,
Speaker 1: but because of a listener request. Uh. This comes from
Speaker 1: Dress Sayan and Dress, I am so sorry if I
Speaker 1: mispronounced your name. I actually asked Drees how to pronounce
Speaker 1: this name, and I can only hope I got close.
Speaker 1: But here's what Dres had to say. Hey, I just
Speaker 1: wanted to ask slash request something about the podcast. See
Speaker 1: a while back, I had a conversation with my dad.
Speaker 1: He commented how amazing it was these days, he can
Speaker 1: just check a website that will pretty accurately tell him
Speaker 1: whether it's going to rain in the next few hours.
Speaker 1: And where I said that, it doesn't seem like that's
Speaker 1: amazing progress to me. After all, when he was a
Speaker 1: kid in the sixties, they wrote would report if it
Speaker 1: would rain the next day, and now it's just that
Speaker 1: we've got it down to a few hours instead of
Speaker 1: twenty four hours ahead. He laughed and said the weather
Speaker 1: report back then was pretty much a joke. Anyway, this
Speaker 1: gave me a lot to think about, and it seemed
Speaker 1: like something to learn about from the Tech Stuff podcast,
Speaker 1: because to be honest, I have no clue how weather
Speaker 1: is accurately predicted. It's just always been there for me.
Speaker 1: So we're gonna talk about weather forecasting, meteorology, the technology
Speaker 1: used to UH to to make predictions, UM, what those
Speaker 1: predictions actually mean. We're gonna break all that down. UH.
Speaker 1: There will probably be at least one or two references
Speaker 1: to how weather report. Weather reports are still largely the
Speaker 1: work of some estimations and best guesses, because, as it
Speaker 1: turns out, whether it's incredibly complicated, but hopefully by the
Speaker 1: end of it you'll have a little bit more sympathy
Speaker 1: for meteorologists, right right, as opposed to my friend who
Speaker 1: in college wrote an essay explaining what level of hell
Speaker 1: meteorologists should inhabit based upon Dante's Inferno, which was kind
Speaker 1: of funny, but also I'm sure meteorologists find it less. So.
Speaker 1: Uh So, let's start off with just talking about the
Speaker 1: history of of predicting weather, and really you have to
Speaker 1: go all the way back to early human civilization because,
Speaker 1: as it turns out, one of the most important factors
Speaker 1: that play a part in this is the fact that
Speaker 1: we humans are pretty good at recognizing patterns. Right, So
Speaker 1: when something happens over and over, we take note of it,
Speaker 1: and we start to look at the other things that
Speaker 1: are happening over and over, and then we start to
Speaker 1: draw some hypotheses. For example, we might think that one
Speaker 1: thing could cause the next thing, or we might think
Speaker 1: one thing simply indicates the next thing is going to happen. Um,
Speaker 1: here's a simple example. Let's say that you are a
Speaker 1: shepherd and you notice that the flock of sheep act
Speaker 1: in a certain odd way every time it's about to rain.
Speaker 1: You might either come to the conclusion that the sheep
Speaker 1: are able to sense the rain before it actually happens,
Speaker 1: and therefore that as an indicator that is going to rain,
Speaker 1: or you might come to the conclusion that, in fact,
Speaker 1: the sheep are causing it to rain. That's probably not
Speaker 1: true that yeah, yeah, so. But eventually you through these
Speaker 1: up survey you start to eliminate possibilities and you start
Speaker 1: to draw some conclusions. Now, in early human civilizations, we're
Speaker 1: talking about very broad conclusions. Things like you notice that
Speaker 1: in general, the weather gets cooler as the year goes on.
Speaker 1: You might not even have a year at this point.
Speaker 1: You may just think, as time passes, the weather gets
Speaker 1: cooler until it gets really cold, and after it's really
Speaker 1: cold for a while, it starts to get warm again,
Speaker 1: and then it gets really warm, and then it gets hot,
Speaker 1: and then the whole cycle starts over. And you may
Speaker 1: also notice that the stars, the way the stars are,
Speaker 1: you can tell that they are. It's a slightly different
Speaker 1: view as this time goes on, and you start to associate, oh,
Speaker 1: when the stars get into this slow you know, this
Speaker 1: kind of configuration, it means we're getting towards the time
Speaker 1: when we should really harvest uh food, because we're about
Speaker 1: to go into the winter months and otherwise we're going
Speaker 1: to lose everything we've been growing. Or when when it's
Speaker 1: this time, we should start playing n ting food because
Speaker 1: it's the best time for us to get a big
Speaker 1: yield later on climate. Yeah, and you start to figure
Speaker 1: out you build out a calendar based on this, and
Speaker 1: that calendar would be fairly rough, you know, wouldn't necessarily
Speaker 1: be reflective of an actual full year, but it would
Speaker 1: be more like an indicator of what you should be
Speaker 1: expecting in the next coming time. Right, So that's your
Speaker 1: basic like big picture stuff, using things like the way
Speaker 1: animals react or certain smells that you might detect before
Speaker 1: a rainstorm. That would be sort of the more acute
Speaker 1: weather type stuff as opposed to the seasonal type stuff.
Speaker 1: And you start to draw those conclusions too, and together
Speaker 1: you start building out general rules that tell you if
Speaker 1: this one thing is happening, then here's what you should expect.
Speaker 1: This sort of pattern recognition. Um. And in fact, today
Speaker 1: some of our data still relies on that principle. It's
Speaker 1: just that we have way more information now at a
Speaker 1: much higher precision than ancient humans did. And and speaking
Speaker 1: of that, I read UM that there are certain Aboriginal
Speaker 1: tribes have been observing their weather patterns for over eighteen
Speaker 1: thousand generations, so that kind of gives you a sense
Speaker 1: of how far back this goes. Yeah, and and of course,
Speaker 1: you know, if you're talking about a very specific region,
Speaker 1: like a very uh, relatively small geographic area, you could
Speaker 1: have a pretty accurate idea of what to expect based
Speaker 1: upon those sorts of observations. Um, they might not be
Speaker 1: presented in the super cool, high tech way that that
Speaker 1: modern meteorology tends to present it, but that doesn't make
Speaker 1: it any less valid. Necessarily. It may be a little
Speaker 1: more rough around the edges. But if you can still
Speaker 1: tell me that, hey, in three days we're gonna get
Speaker 1: some rain, and three days later it rains, and you
Speaker 1: do that reliably, that's pretty impressive. Right. So, uh, if
Speaker 1: you want to start looking at people who were really
Speaker 1: thinking about whether in kind of almost a scientific sense,
Speaker 1: and one of the first people you would have to
Speaker 1: look at his Aristotle. Um, big brain Aristotle, he was.
Speaker 1: He was quite the thinker. He wrote about whether in Meteorologica,
Speaker 1: and he came up with a bunch of hypotheses, some
Speaker 1: column theories, I would say, hypotheses because none of these,
Speaker 1: not all of these proved true, but came up with
Speaker 1: some hypotheses about how stuff like rain and hail and
Speaker 1: wind and clouds and thunder and lightning and hurricanes, what
Speaker 1: made them happen, how did they behave what were the
Speaker 1: rules that governed them? And some of his ideas were
Speaker 1: mostly right and some of his ideas were way off.
Speaker 1: But the problem was without ways to measure the various
Speaker 1: metrics associated with weather, it was kind of impossible to
Speaker 1: say one way or the other. So for about two
Speaker 1: thousand years, everyone kind of just went with it because
Speaker 1: you didn't have any way of proving or disproving any
Speaker 1: of the individual ideas. But you need you need a basis. Yeah,
Speaker 1: you know, at least it was something. It was at
Speaker 1: least something to work from. It was just it was
Speaker 1: just a question of time. When would people develop tools
Speaker 1: that would allow them to put these ideas to the
Speaker 1: test and either uh, see which ones are mostly right
Speaker 1: but maybe need some tweaking, or which ones you can
Speaker 1: just completely throw out the window, Which brings us up
Speaker 1: to the Renaissance, one of my favorite time periods. As
Speaker 1: it turns out, spent a lot of time there. Our
Speaker 1: listeners can't see. But right now Jonathan has a handlebar mustache,
Speaker 1: a giant handlebar mustache. Because the character I play in
Speaker 1: the Georgia Renaissance Festival has such a mustache. And uh,
Speaker 1: and I will be performing as that character the day
Speaker 1: after we record this episode. It's a weekend for the
Speaker 1: Georgia Renaissance festivals. Would you say that someone might have
Speaker 1: a handlebar mustache in the fifteenth century, around the time
Speaker 1: of German philosopher Nicholas of Cusa, It's quite possible. Um,
Speaker 1: I mean, there's no reason they could not have one.
Speaker 1: What's not like there were social taboos about such things. Uh. Yeah,
Speaker 1: So this philosopher, Nicholas of Cusa, designed a device to
Speaker 1: measure the amount of moisture in the air. Uh. And
Speaker 1: we call these hygrometers. These are it's really kind of
Speaker 1: a way of measuring humidity, which here in Atlanta you
Speaker 1: can pretty much just say it's it's humid. It's so humid. Yeah,
Speaker 1: the humidity in Atlanta is brutal, to the point where
Speaker 1: I have friends who come in from Texas where the
Speaker 1: temperatures and Texas can get twenty degrees hotter than it
Speaker 1: gets here in Atlanta. But because Texas has relatively low
Speaker 1: humidity through most of the state, they think the weather
Speaker 1: here is way worse, like, way more difficult to deal with.
Speaker 1: But how do you measure that? And he came up
Speaker 1: with an interesting idea. Now there's no there's no indication
Speaker 1: that he ever built the device he came up with,
Speaker 1: but he said, what you do is you take a
Speaker 1: set of balanced scales, so you know what those look like.
Speaker 1: They have a little dish on either side, and on
Speaker 1: one side you put a large amount of wool, and
Speaker 1: on the other side you put some some weights. He
Speaker 1: said stones. Other people later on said discs of wax
Speaker 1: didn't really matter. It just had to be a counterweight
Speaker 1: of some sort. Now, the purpose of the wool is
Speaker 1: to soak up moisture in the atmosphere, which would make
Speaker 1: the wool get heavier. This is what Nicholas was saying, Like,
Speaker 1: the wool will get heavier as it soaks up water
Speaker 1: from the air, and you'll be able to tell that
Speaker 1: because the scales will start to shift and you'll see
Speaker 1: that the the side with the wool will start to
Speaker 1: get heavier. Then if it dries out, if the weather
Speaker 1: gets dry, the wool will start to lose moisture, it
Speaker 1: will evaporate, and you'll start to see that side of
Speaker 1: the scale moving up. It'll get lighter. Now, he never
Speaker 1: built that, but another big thinker of the Renaissance did
Speaker 1: get around to it, Leonardo da Vinci. He did everything. Yeah,
Speaker 1: when he wasn't building helicopters or designing tanks, which he
Speaker 1: never built, but he did design. He designed a tank,
Speaker 1: and he designed a really weird um I think gosh,
Speaker 1: it was something like a thirty three barrel gun didn't
Speaker 1: eat the I think a diving suit as well. Pretty
Speaker 1: much any any sort of thing that in the Renaissance
Speaker 1: would sound like it's science fiction that she had some
Speaker 1: sort of hand in. He probably has a primitive tablet
Speaker 1: schematic somewhere. Yeah, yeah, he probably at one point came
Speaker 1: out to his patrons and showed a wooden slate and
Speaker 1: talked about how if you ran your fingers across it,
Speaker 1: you could, uh, you could pageanate through. And then he'd say,
Speaker 1: I think you're gonna love it, and maybe even did
Speaker 1: a one more thing. Um So that was the first
Speaker 1: kind of weather related um uh instrument that people were
Speaker 1: really thinking about. Another would come in the seventeenth century.
Speaker 1: Early sires usually put around sixteen o three when physicist
Speaker 1: Galileo Galile created a thermoscope, which is sort of a
Speaker 1: predecessor to a thermometer. And it was a pretty simple idea.
Speaker 1: So you start with a container that has a small
Speaker 1: amount of liquid in it, usually water. That's your base.
Speaker 1: And then you also have a kind of a hollow
Speaker 1: tube of glass that ends in a bulb, so like
Speaker 1: a larger bulb at one end and open on the
Speaker 1: other end, and you could do something like warm the
Speaker 1: bulb if you want to, in your hands. But then
Speaker 1: you would put the bulb, you put the tube into
Speaker 1: the small container of water. The bulb would be suspended
Speaker 1: above it. Usually the hollow uh straw like tube would
Speaker 1: be long enough, you know, several inches long. You could
Speaker 1: then observe that as the temperature of the bulb changed,
Speaker 1: the level of water in the tube would either go
Speaker 1: up or go down. And this is because the air
Speaker 1: inside the tube is either expanding or contracting, depending upon
Speaker 1: whether it's heating up or cooling down. And this wasn't
Speaker 1: a thermometer, but it was it was interesting, and it
Speaker 1: was once again a start. Yeah, later on someone looked
Speaker 1: at Galileo's little invention and said, what if we put
Speaker 1: like markings on the tube so you could say how
Speaker 1: many steps up or down the tube it went. Then
Speaker 1: we could even give indications of how much warmer or
Speaker 1: cooler a guy. You could say that it's four steps
Speaker 1: warmer or four steps cooler. That became the basis of
Speaker 1: the thermometer. So and that didn't take long. It was
Speaker 1: within about fifty years that that you had the first
Speaker 1: working thermometers. Following this this kind of proof of concept thermoscope,
Speaker 1: there was also there is the Galilean thermometer. Are you
Speaker 1: familiar with these? You've probably seen one. They are the
Speaker 1: cylindrical glass. They're usually very decorative for for like home
Speaker 1: office deskers, and but there these glass tubes. They are cylindrical.
Speaker 1: Typically inside they have these these little glass blown glass
Speaker 1: balls that contain their own liquid. Often it's a liquid
Speaker 1: that has dye in it, so they're blue or green
Speaker 1: or red or whatever. And each one has a little
Speaker 1: weight attached to it that has a temperature. And what
Speaker 1: happens is the balls represent different densities of water, and
Speaker 1: the temperature of the glass tube will change the density
Speaker 1: of the water inside the glass tube, and then you'll
Speaker 1: see whichever ball is at the bottommost of the tube
Speaker 1: the glass tube, as that represents the general temperature, and
Speaker 1: they tend to be between like you know, like about
Speaker 1: five degrees apart, so you might have sixty five degrees
Speaker 1: seventy seventy five degrees eighty that kind of thing. So
Speaker 1: whicheveryone's at the lowest point, that's the temperature of the water,
Speaker 1: thus the temperature of the areas surrounding it. I tend
Speaker 1: to be used, like I said, as decorations for desks
Speaker 1: and stuff. Galileo actually did not invent that, but some
Speaker 1: of his students did. It was several of his students,
Speaker 1: so that's why it's called a Galilean thermometer's neat. Yeah. Yeah,
Speaker 1: it's a very pretty way of seeing, generally speaking, what
Speaker 1: temperature the tube is and therefore probably what temperature the
Speaker 1: surrounding air is. Keeping in mind that water changes temperature
Speaker 1: more slowly than uh than something like a room would,
Speaker 1: so it wouldn't be reflected immediately, but it's still kind
Speaker 1: of interesting. Then we have the barometer. This is a
Speaker 1: very important tool in uh predicting the weather. So barometer
Speaker 1: is all about predicting or not predicting, but measuring atmospheric pressure.
Speaker 1: So first, just in case you weren't aware, the atmosphere
Speaker 1: exerts pressure on us. It pushes down. Gravity is technically
Speaker 1: pulling down on the atmosphere. So the lower you are
Speaker 1: to the surface of the air, like the closer the
Speaker 1: lower down in elevation you are, the more pressure you
Speaker 1: feel from atmosphere. This is why as you climb a mountain,
Speaker 1: where you get on a plane, you experience lower amounts
Speaker 1: of air pressure. It's also why you have to pressure
Speaker 1: eze aircraft that fly it pretty high altitudes, otherwise you
Speaker 1: would suffer some pretty rough effects. Um. And on the
Speaker 1: Earth surface, the force of gravity. Due to the force
Speaker 1: of gravity, the pressure is about fourteen points seven pounds
Speaker 1: per square inch. Yeah, that's a sea level. Yeah, that's
Speaker 1: what we call an atmosphere of pressure. Right one atmosphere
Speaker 1: of pressure. You look at it at sea level. Specifically,
Speaker 1: you're looking at it at sea level at fifty nine
Speaker 1: degrees fahrenheit, which is fifteen degrees celsius. Uh. You have
Speaker 1: to be very specific because temperature will change pressure as
Speaker 1: as you warm up air. Uh. Typically this is just
Speaker 1: a general rule of thumb. When something warms up, that
Speaker 1: means molecules are moving. That's that's the energy of motion. Ultimately,
Speaker 1: you're making these molecules move faster, and that's kind of
Speaker 1: what heat looks like. So as molecules of air move
Speaker 1: around more, they spread out more, it becomes less dense.
Speaker 1: So that would change the atmospheric pressure as well. That's
Speaker 1: why you have to take temperature into account. When you
Speaker 1: talk about one atmosphere of pressure. That's very specific. It's
Speaker 1: at sea level at that temperature, that's one atmosphere um
Speaker 1: So that's that's kind of interesting. Anyway. The first person
Speaker 1: to actually create a barometer, it was a guy by
Speaker 1: the name of Evangelista Toricelli, and h the first invention
Speaker 1: people just called tori Chelli's tube, which doesn't seem very dignified. No,
Speaker 1: it needs a special name, Yeah, but tore Chelli's tube,
Speaker 1: it wasn't quite the barometer yet. What he was doing
Speaker 1: was he was actually experimenting with the concept of vacuums,
Speaker 1: like creating a vacuum within an within a tube or
Speaker 1: some other container. He was just it was one of
Speaker 1: those things where we didn't fully understand what that was
Speaker 1: how it worked, and so he did this experiment. He
Speaker 1: was actually friends with Galileo, and Galileo said, hey, Evangelista,
Speaker 1: I got an idea for you. Why don't you take
Speaker 1: one of those tubes you've been working with and fill
Speaker 1: it with mercury and use that in your vacuum experiments.
Speaker 1: Will be a lot easier to see than some other liquid.
Speaker 1: And toward Cheli says, all right, I'll give it a shot.
Speaker 1: So he took a four ft long glass tube and
Speaker 1: he filled the glass tube with mercury so it was
Speaker 1: closed on one end, open on the other, and then
Speaker 1: he inverted the tube into a dish, and the dish
Speaker 1: had a little bit of mercury at the bottom of it,
Speaker 1: and it showed that despite the fact that the top
Speaker 1: of the tube, you know, like the mercury went all
Speaker 1: the way up this four foot tube, the liquid didn't
Speaker 1: just come rushing out and spill everywhere, right, because the
Speaker 1: vacuum is what held it him place. And he says, look, see,
Speaker 1: I was so smart. This shows that there's something working here.
Speaker 1: We're gonna really explore this. But then he noticed something
Speaker 1: else that was really interesting. He noticed that despite the
Speaker 1: fact that the tube could stay upright and the liquid
Speaker 1: would stay in there. From day to day, there are
Speaker 1: variations and how high the mercury would be in the tube.
Speaker 1: And it wasn't just sinking down. It's not like it
Speaker 1: was leaking over the course of a week. So like
Speaker 1: you come back and it's a couple inches lower, and
Speaker 1: then the next day it's a couple of inches lower.
Speaker 1: It wasn't like that. Some days it was actually higher.
Speaker 1: And he started thinking, well, what the heck would cause
Speaker 1: the mercury to go up or down this tube. The atmosphere,
Speaker 1: that's it. The atmospheric pressure pressing down on the liquid
Speaker 1: in the dish. That's what determined whether the the well,
Speaker 1: that's what determined the height of the mercury inside the tube.
Speaker 1: So on days with higher atmospheric pressure, it pushes down
Speaker 1: on that that exposed liquid within the dish, and it
Speaker 1: forces that liquid to go up the tube, and and
Speaker 1: so the height of the liquid inside the tube goes up.
Speaker 1: On days where atmospheric pressure is lower, some of that
Speaker 1: liquid comes down and starts filling up the dish until
Speaker 1: it reaches that kind of equilibrium. And then he so
Speaker 1: he said, hey, this shows that the atmosphere itself exerts pressure.
Speaker 1: And not only that, but the pressure is not consistent
Speaker 1: day to day, can change. And uh in Torchelli built
Speaker 1: the first mercury barometer, So now he was building something
Speaker 1: specifically to measure this thing, because before he was really
Speaker 1: demonstrating the concept of vacuums. So now we've got the barometer,
Speaker 1: we've got the thermometer, we've got the hygrometer, essential things. Yeah,
Speaker 1: these are the basics for taking measurements about weather. And
Speaker 1: at that point it was really the start of gathering
Speaker 1: enough information so that meteorology, the science of meteorology, could
Speaker 1: actually exist, right because now we could not just observe patterns,
Speaker 1: we could actually quantify what was happening. And by quantifying it,
Speaker 1: we could get to this level of precision where we
Speaker 1: could start to draw more uh uh specific conclusions as
Speaker 1: to what would or would not happen based upon current conditions.
Speaker 1: So all that being said, we still have some issues
Speaker 1: predicting weather. So why is that? Well, like I said before,
Speaker 1: it's complicated. So here's the thing. Our atmosphere is fluid.
Speaker 1: It's a gas, but it behaves via fluid dynamics. Dylan,
Speaker 1: have you ever studied fluid dynamics. I studied them in physics,
Speaker 1: and they are brutally difficult to comprehend because it can
Speaker 1: get so there's so many factors that can affect a
Speaker 1: fluid so and the Earth has a whole bunch of
Speaker 1: them happening at once. Right. First of all, there's this
Speaker 1: big ball of plasma that's about eight and a half
Speaker 1: light minutes away from us. It's called the Sun. Yeah,
Speaker 1: uh you know, on on nice days you might even
Speaker 1: get a glimpse of it. So the Sun provides obviously
Speaker 1: a ton of energy to the Earth and uh so
Speaker 1: we so the Earth absorbs a lot of solar radiation
Speaker 1: and that can affect fluid dynamics because you've got a
Speaker 1: lot of heat coming into a system. On top of that,
Speaker 1: you've got the Earth there. It's not standing still, the
Speaker 1: Earth's rotating. That rotational force creates other fluid i effects
Speaker 1: in the atmosphere. We'll talk about those specifically. When we
Speaker 1: get too high and low pressure systems. Um you've got gravity,
Speaker 1: which is pulling down on the fluid, so that's another
Speaker 1: force that's in play. You've got differences in surface temperature
Speaker 1: on the Earth, so you've got areas where it's very cold,
Speaker 1: versus are is that are very hot that in turn
Speaker 1: affects the atmosphere and can change things around. You have
Speaker 1: air currents, a big deal there. That's also partially due
Speaker 1: to the rotation of the Earth. You've got mountain ranges
Speaker 1: which can act as like a windbreaker for certain things.
Speaker 1: That changes the way whether patterns happen. Lots of things
Speaker 1: that are all in play, and some of these are localized,
Speaker 1: and some can concern large portions like air movement. Oh yeah, yeah,
Speaker 1: some of them are are Some of the effects of
Speaker 1: these can be felt hundreds of miles from where the
Speaker 1: thing happened, right, which makes it even harder because you know,
Speaker 1: as a lady person, you sit there and think, all right, well, um,
Speaker 1: you know, because I can't see any clouds on the horizon,
Speaker 1: I think tonight is going to be all right. And
Speaker 1: then you could have a very fast moving system coming
Speaker 1: in due to something that happens well out of sight. Uh.
Speaker 1: It's it ends up creating a lot of things that
Speaker 1: could be counterintuitive depending upon what you have at your disposal.
Speaker 1: Like of course, the more information you have, the better
Speaker 1: conclusions you can draw. In general, assuming that you also
Speaker 1: know what you're talking about, um, so let's talk about
Speaker 1: some of these things, these different major components that shape weather,
Speaker 1: like atmospheric pressure. So we just talked about that with barometers,
Speaker 1: But what does that mean? So what is happening? Uh? Well,
Speaker 1: I talked about how you have warm air that has
Speaker 1: air moving around a lot. That means it ends up
Speaker 1: spreading out, it becomes less dense than cold air. You
Speaker 1: probably have heard the phrase that warm air rises and
Speaker 1: cold air sinks. That's not not entirely accurate as to
Speaker 1: what's going on. What's really happening is cold air is
Speaker 1: more dense than warm air, so cold air comes to
Speaker 1: take up the space that warm air had, which forces
Speaker 1: warm air to go up. So it's not so simple
Speaker 1: as warm air rises cold air sinks. It's more like,
Speaker 1: you know, if you've got these big heavy weights at
Speaker 1: the top and then they're going to come they quote
Speaker 1: unquote one, there's no desire, but they have a tendency
Speaker 1: to want to move downward, forcing the lighter stuff to
Speaker 1: go upward. That's pretty much what's happening here. So when
Speaker 1: you're talking about our atmosphere, you have to keep in
Speaker 1: mind it's three dimensional. It's not on a flat plane.
Speaker 1: That's easy to forget when we look at weather reports,
Speaker 1: because we're looking typically at a flat map, right that
Speaker 1: has a bunch of stuff like it's got little flags
Speaker 1: all over it and little lines around it and h
Speaker 1: and l's, and you're wondering, what you know, maybe there's
Speaker 1: some clouds in there too, and but but typically you're
Speaker 1: looking at a two dimensional representation. But really you have
Speaker 1: to remember that weather is a three dimensional phenomenon, so
Speaker 1: that makes it a little more complicated. Um. Also, you
Speaker 1: gotta remember the water cycle. So cold air can't hold
Speaker 1: onto moisture the way warm air can. All right, when
Speaker 1: you have warm air as close to the surface. Let's
Speaker 1: say you've got some nice, warm moist air close to
Speaker 1: the surface of of the the planet, and cold air
Speaker 1: is sinking down forcing the warm air up. As the
Speaker 1: warm air rises, it's going to start to cool and
Speaker 1: as it cools, it can no longer hold onto the
Speaker 1: moisture that it had, which means the moisture starts to condense,
Speaker 1: water vapor begins to condense. This is how you get
Speaker 1: clouds and ultimately how you get stuff like precipitation. So
Speaker 1: understanding that's important. So now let's let's imagine way up
Speaker 1: in the atmosphere, at the top level of where our
Speaker 1: weather happens, we have these massive air currents now. In
Speaker 1: cases where air currents are converging together, so you've got
Speaker 1: two air currents that are meeting up, they start to
Speaker 1: force air out of the way. Now air can't go
Speaker 1: any further up, it has to go down. That's the
Speaker 1: only place to go. So that air coming down increases
Speaker 1: air pressure at that location. You have air moving down
Speaker 1: towards the surface of the earth pushing down, your air
Speaker 1: pressure goes up. So an area of high pressure. You
Speaker 1: know what kind of weather you typically see in an
Speaker 1: area of high pressure, clear, dry weather, Yes, exactly. So
Speaker 1: when you have high pressure system, it's typically pushing the
Speaker 1: moisture out of the way. It's it's it tends and
Speaker 1: we have to use phrases like tens or words like
Speaker 1: tens because it's not every case is is equal. But
Speaker 1: it tends to be cooler, it tends to be uh sunny,
Speaker 1: it tends to have less wind than low pressure systems.
Speaker 1: Um So this high pressure system creates pleasant weather. Low
Speaker 1: pressure systems are different. Oh and also if you were
Speaker 1: to view this from the sky like you're above this
Speaker 1: high pressure system, and if you could see air, first
Speaker 1: of all, that would be a nightmare. But if you could,
Speaker 1: you would see that this this, uh, the air is
Speaker 1: not just coming down like a column. It's not like
Speaker 1: it's not like you turn on a spigot of water
Speaker 1: and water just falls straight down. It's actually turning as
Speaker 1: the air is sinking right as this high pressure system
Speaker 1: push forces air downward, and it actually moves in a
Speaker 1: clockwise direction, which is funny because I was looking at
Speaker 1: Dylan a second ago and making a twisting motion, but
Speaker 1: I was doing counterclockwise. But no, it moves in a
Speaker 1: clockwise direction. This is, by the way, due to the
Speaker 1: rotational force of the Earth in part. So you've got
Speaker 1: this rotating clockwise system that's pushing air downward. That's your
Speaker 1: high pressure. So that's your nice weather blow pressure. I
Speaker 1: think you can probably take a wild guess it's gonna
Speaker 1: mean crummy weather. Yeah, this is where you're getting clouds
Speaker 1: and rain. And typically you're talking about air being pulled upward.
Speaker 1: So why is air getting pulled upward? Well, remember I
Speaker 1: was talking about those those currents up in the upper
Speaker 1: atmosphere where they were converging together and forcing air downward.
Speaker 1: If the currents are moving apart from each other, if
Speaker 1: they're diverging, they create sort of a vacuum effect over
Speaker 1: that region, and that starts to pull air upward, creating
Speaker 1: an area of low pressure. Warm air from the surface
Speaker 1: gets pulled upward, it starts to cool down, and the
Speaker 1: water vapor condenses. That's where you start getting those overcast days,
Speaker 1: the cloudiness, the rain um And on top of that,
Speaker 1: you're creating since since it's a low pressure system, you're
Speaker 1: creating the opportunity for some pretty hefty winds to move in. Right,
Speaker 1: Because air is always going to move from an area
Speaker 1: of high pressure to an area of low pressure. That's
Speaker 1: just pure fluid dynamics. It makes a lot of sense
Speaker 1: if you've got uh like, imagine that you have two
Speaker 1: water balloons connected to each other, all right, and they
Speaker 1: they are in equilibrium, so they're equally full, not totally full,
Speaker 1: but equally full. If you're to squeeze one of those,
Speaker 1: creating an area of high pressure, it forces the water
Speaker 1: to go to the area of relatively lower pressure. Right,
Speaker 1: You're forcing water into that second water balloon. Same thing
Speaker 1: is true with low pressure systems. You've got a low
Speaker 1: pressure area. That means, uh, any area around it has
Speaker 1: higher pressure, air is going to want to move into
Speaker 1: the area of lower pressure. That's where you get get
Speaker 1: winds coming in and it can get pretty breezy. So
Speaker 1: this one, if you were to look overhead and view
Speaker 1: the air, it would be rotating in a counter clockwise
Speaker 1: or witter shins if you are Shakespearean direction, and the
Speaker 1: air would be coming into the low pressure system as
Speaker 1: opposed to coming out like in high pressure. It would
Speaker 1: all be moving outward in that clockwise direction, with low
Speaker 1: pressure inward in a counterclockwise direction. Uh. Now, the reason
Speaker 1: why I even bring this up is because it's important
Speaker 1: to understand how high at pressure and low pressure affect weather.
Speaker 1: So things like you're the wind speed, the um the
Speaker 1: potential for precipitation or lack of precipitation, all of those
Speaker 1: would play a part, and it's important for you to
Speaker 1: know what the pressure is of that region in order
Speaker 1: for you to make any sort of forecast um. So
Speaker 1: the barometers would be the tools you would use to
Speaker 1: get those those measurements. Now, the old style barometers, the
Speaker 1: mercury ones, use fluid to indicate changes in pressure sort
Speaker 1: of like what we were talking about with Evangelista's barometer. Uh,
Speaker 1: simply just looking to see where where the level is.
Speaker 1: So area of high pressure pushes the liquid further up,
Speaker 1: you would say that pressure is rising and whether it's
Speaker 1: probably gonna be pretty nice. In fact, if you ever
Speaker 1: have seen one of those old school barometers, it probably
Speaker 1: has like sunny like a little drawing of sunshine towards
Speaker 1: the top of it where the level goes up. If
Speaker 1: the if the glass is falling, if the mercury is
Speaker 1: going down the tube, then that would suggest low russure,
Speaker 1: which suggests cloudy, nasty weather. But we also have other
Speaker 1: types of barometers. In fact, not a lot of people
Speaker 1: use the mercury ones anymore. Don't know. If you know this,
Speaker 1: Dylan is not the best thing to use. It's a
Speaker 1: little toxic. It'll drive you crazy, you'll go mad as
Speaker 1: a hatter um. But yeah, they they they're also aneroid barometers,
Speaker 1: which were invented in the nineteenth century eight hundreds. In
Speaker 1: other words, these have a tiny little metal box and
Speaker 1: the sides are all made of of a flexible metal,
Speaker 1: and changes in pressure either push the sides of the
Speaker 1: box inward or allow the sides of the box to
Speaker 1: flex outward. That in turn is connect to tiny little
Speaker 1: levers which are connected to a needle. And then you
Speaker 1: look at your your device. It can look like a
Speaker 1: little stop watch actually, and you see where the needle
Speaker 1: is and that tells you where the atmospheric pressure is
Speaker 1: at right, Or you could use uh digital barometers, which
Speaker 1: have little pressure sensitive transducers that essentially do the same thing.
Speaker 1: They're just doing it with a transducer as opposed to
Speaker 1: an actual physical metal box. And how do we talk
Speaker 1: about these measurements, Well, it depends upon what system you're
Speaker 1: looking at. But typically whether men meteorologists, I should say,
Speaker 1: whether people. I suppose um that that sounds like a
Speaker 1: good term, yeah, weather people, M Yeah, Meteorologist is probably
Speaker 1: more accurate, but they use they tend to use millibars
Speaker 1: to describe atmospheric pressure. But in the US. Here in
Speaker 1: the US, we sometimes refer to inches of mercury because
Speaker 1: darn it, we like that system. The standard scientific unit
Speaker 1: is the pascal or p A. And then there is
Speaker 1: of course the one atmospheric pressure type approach. That's not
Speaker 1: terribly useful if you're talking about tiny changes in atmospheric pressure,
Speaker 1: like it's a point zero zero zero six atmosphere change.
Speaker 1: It's not doesn't help you very much. Um to me,
Speaker 1: it's kind of like measuring temperatures and celsius. It works
Speaker 1: great if you're boiling water, but if you're doing anything else,
Speaker 1: Celsius to me is just it's too brute force an
Speaker 1: approach to describe water. So that's perfect, right, that's really
Speaker 1: whenever I go by Dylan's desk, it's just a pot
Speaker 1: of boiling water and some photos on a screen, and
Speaker 1: that's about it. Uh So, then we have temperature and
Speaker 1: moisture that those are the other two really big components.
Speaker 1: Um So, a large body of air that has a
Speaker 1: similar temperature and moisture throughout that body of air is
Speaker 1: called an air mass. So when two air masses are
Speaker 1: near one another, they are separated by a thing called
Speaker 1: a front. Right. So you've heard of cold fronts and
Speaker 1: warm fronts obviously, right, So we'll focus on the United States.
Speaker 1: We have four major types of air masses that affect
Speaker 1: our weather here in the United States. This is not
Speaker 1: the way it is everywhere. These are the four that
Speaker 1: that in general affect our weather. Um So you've got
Speaker 1: continental polar air masses cold and dry, continental tropical air
Speaker 1: masses hot and dry, yes, which by the way, only
Speaker 1: happened in the summer, and come up from Central America.
Speaker 1: That makes sense. Yeah, then you have maritime polar cool
Speaker 1: and moist. Yeah, and boy, I'm so sorry for you
Speaker 1: people out there who hate the word moist. And then
Speaker 1: maritime tropical warm and moist. There it is again. Yeah.
Speaker 1: So your continental polar air masses, those tend to come
Speaker 1: from our our friends to the north Canada. They ship
Speaker 1: us their poutine, they're Tim Horton's coffee, and they're continental
Speaker 1: polar air masses. Don't bring up Tim Hortons. I'm still
Speaker 1: bummed that there's not one here. I'm actually still look Canada.
Speaker 1: I poke a lot of fun, but I fully admit
Speaker 1: Tim Horton's is a phenomenal chain, national treasure. I would
Speaker 1: welcome it with open arms to come here to Atlanta.
Speaker 1: Just throwing it out there. Um, your continental tropical, like
Speaker 1: I said, comes up through Central America and typically only
Speaker 1: affects our weather in the summer. Maritime polar uh, that
Speaker 1: tends to come from the far northeast. So we're talking
Speaker 1: like in the New England, that area maritime tropical pretty
Speaker 1: much everywhere else um And by tropical, when we say
Speaker 1: hot or warm and moist, we don't necessarily mean like
Speaker 1: it feels like you're in the Caribbean. It just means
Speaker 1: not not cold. Right. So the fronts tell us what
Speaker 1: sort of air is moving into an area. So a
Speaker 1: warm front, first of all, they tend to move pretty slowly.
Speaker 1: Warm fronts are not known for moving through an area quickly,
Speaker 1: and they bring lots of rain because warm fronts are
Speaker 1: pushing out cold air. So imagine you've got a massive
Speaker 1: cold air in an area. A warm front is coming
Speaker 1: in that warm air when it encounters the cold air
Speaker 1: that's already in that region, it's the warm hair's inclination
Speaker 1: is to kind of go up the cold air like
Speaker 1: a ramp because again, the cold air is more dense, right,
Speaker 1: so the warm air can't just push it all the way.
Speaker 1: The warm air is less dense than the cold air,
Speaker 1: but it can start to go up on top of it,
Speaker 1: which means the warm air starts to cool down exactly,
Speaker 1: and that's why we get rain and at the at
Speaker 1: the edge of a warm front. So they move pretty
Speaker 1: slowly because warm air just doesn't push cold air out
Speaker 1: very efficiently, and we get a lot of precipitation. Cold
Speaker 1: fronts where cold air replaces warm air, move faster and
Speaker 1: tend to have intense but short thunderstorms and other precipitation.
Speaker 1: Is the front moves in and the weather tends to
Speaker 1: clear up pretty shortly thereafter. The reason for this is,
Speaker 1: imagine you've got a mass of cold air moving in,
Speaker 1: you have warm air in the region. The cold air
Speaker 1: is going to almost act like a shovel scooping up
Speaker 1: that warm air, pushing it up into the upper levels
Speaker 1: of the atmosphere, of the lower level of the atmosphere,
Speaker 1: but the upper side of it, which cools that that
Speaker 1: air down very quickly. Because of that quick cooling, you
Speaker 1: get things like bigger rainstorms thunderstorms, but they tend to
Speaker 1: happen very quickly, and then once the front has moved through,
Speaker 1: things are okay again. Spend a summer in Atlanta and
Speaker 1: you will you will see this phenomenon repeatedly. Right like
Speaker 1: you there was. There are times where, if it's a
Speaker 1: particularly humid month, you might be able to set your
Speaker 1: watch by when the thunderstorm is going to come through.
Speaker 1: The extreme, extreme versions of it as well, not not
Speaker 1: not disaster level, but you'll see quick uh intense thunderstorms
Speaker 1: with hail and heavy rains, and they will be gone
Speaker 1: in an hour or two, and then it just becomes
Speaker 1: a steam bath for the city. That's Atlanta most of
Speaker 1: the time. Yeah, but it's particularly bad about an hour
Speaker 1: after a thunderstorm. It's probably the most miserable Atlanta fields,
Speaker 1: right because it's just it's like walking into a steam room.
Speaker 1: So again, the reason for that that fast violent weather
Speaker 1: is just the speed at which that warm air is
Speaker 1: being pushed up and cooled down so that it can
Speaker 1: no longer hold on to all this moisture that was
Speaker 1: once part of it um and it has to go somewhere,
Speaker 1: so it lands on us. So that's kind of interesting.
Speaker 1: They're also stationary fronts. Stationary fronts are when two fronts
Speaker 1: just kind of collide and that's it. They're just there.
Speaker 1: It's gonna stick around for a while, you have a
Speaker 1: lot of rain. Typically sounds like the traffic jam of fronts. Yeah,
Speaker 1: and then there's occluded fronts, and that's when a warm
Speaker 1: front gets caught between two cooler air masses. Uh So
Speaker 1: the warm front gets pushed up and we get a
Speaker 1: lot of intense thunderstorms with included fronts to Dylan and
Speaker 1: I had a lot more to say about whether As
Speaker 1: it turns out, it's pretty complicated stuff if you hadn't
Speaker 1: picked up on that already, And so, in order to
Speaker 1: preserve your sanity and and ours, we've decided to split
Speaker 1: this episode up into two after we had recorded the
Speaker 1: whole thing, So make sure you tune into next week's
Speaker 1: episode for the thrilling conclusion about how weather technology works
Speaker 1: and what all those predictions actually mean, because we dive
Speaker 1: into that and explain how the meteorologists put together things
Speaker 1: like weather forecasts, and it was a really fun experience
Speaker 1: to talk about all of that. In the meantime, if
Speaker 1: you have any suggestions for future episodes of Tech Stuff,
Speaker 1: or maybe there's someone you would love to have on
Speaker 1: the show as a guest interview or guest host, let
Speaker 1: me know. My email address is tech Stuff at how
Speaker 1: stuff works dot com, or draw me a line on
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Speaker 1: tech Stuff hs W and I'll talk to you again
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