Transcription
Well, today's nice because, uh, we kind of get into the meat and potatoes of this class, uh, which is all about learning about weather, uh, that we can use, of course, uh, daily as we fly aircraft, which is kind of nice. So whether you're flying privately or commercially, uh, some of the bigger stuff later on, uh, all the stuff that you'll be learning in my class should be usable, uh, regardless of what level of flying that you're going to be, uh, at. So a lot of good basics that you, uh, can kind of start your adventure. It's kind of like when you get your private pilot license, right? So when you first get that, uh, it's, you know, you've heard probably several times, if not, uh, that it's a license to learn, and it truly is. I mean, there are other things like it's probably one of the safest times you'll be as a pilot because you know you've worked so hard to get to that point and fly as perfectly as you can, right? Uh, that that's probably when you are actually the safest. It just goes downhill from there. No, just joking. Anyway, um, all the stuff that's uh going to be taught in this class will be practical, which is nice. So we'll go ahead and get into it, which is nice. Start off with this picture of a part of the globe, right? And you can see some of the atmosphere. It looks like that blue haze that's on the horizon, and then, of course, all the clouds and other weather that are located on the globe that you can see. Uh, this is kind of a neat picture that I go to every once in a while, and sometimes you can pick out some things as you get into this class a little bit more that makes sense when you look at this picture. So eventually you'll be able to see the thunderstorms, the, uh, stuff like maybe mountain waves or disturbances in the atmosphere just by looking at pictures, which is kind of nice.
This picture also kind of gives you an example of how thin our atmosphere is. So even though, you know, when we go through like today and we can see the altitude that our atmosphere goes up to, uh, most of it, the bulk of the density part of our atmosphere is, uh, in the troposphere area, about 36,000 ft, and about 50% of the pressure of our atmosphere is located at 18,000 ft or below, down to the surface. So it's pretty wild. So as we start to get through this, you'll see it today what our atmosphere is made up of, and and, uh, all the protections that we have because our world is spinning around 1000 miles an hour at the equator. But before we get into that, we'll look at what meteorology is. So this is kind of like a little historical, uh, slide listing, uh, the the evolution of the word meteorology and, uh, back in the day when they described meteor, uh, in Greek, of course, um, if the the purpose of using that word was there was it was how they studied, uh, up in the higher atmosphere or things that are higher in the air. So that's where that word originally comes from. It's, uh, of course not, doesn't have anything to do with, you know, studying meteors, though that might be pretty cool if you're into that. Um, but of course, it evolved to where it is today around the 17th century or the 1600s, uh, into meteorology.
So we're going to be studying a bunch of different things in this class that includes, uh, like temperature, pressure, uh, water vapor, and of course, uh, larger air mass flows, uh, as we go through this class. So, uh, being able to understand kind of some of those larger air masses as it moves around and it gives us different types of weather based upon the pressure, uh, we'll talk about that, and and I'll point out as much as I can, uh, some of the stuff that might be asked by a DPE or a designated pilot examiner, uh, during your private, commercial, instrument, that kind of stuff, uh, as we go along. So, uh, we'll go ahead and start off because it's a science-based course, right? The atmospheric science discipline, which is the overall kind of umbrella atmospheric science, studies the entire atmosphere, but of that atmosphere is broken into three different subdisciplines, uh, that you just need to know exist, even though we're only going to study one of them, uh, in this class. But the first one that you'll be familiar with, uh, at least generally, is climatology, or or study of the climate. It's kind of always in the news, uh, but in this case, climat is simply kind of weather over a very long period of time, like a hundred years or more, um, where you get certain types of climate, uh, in different parts of the world. And so when we get into like global circulation and stuff, you'll start to understand, oh, that's why there's a huge desert right there, or there's, you know, that's why the rainforests exist, uh, well, because is because of this global circulation which creates the climate, and of course, there's weather within each climate, and we, you know, obviously have to, uh, recognize that, uh, but climatology remember is just something that's over a longer period of time, uh, and since we fly usually on that same day or a day or two or maybe, you know, let's say you have a four days, so you have a week that you have to plan for, uh, or if you're flying a G650 or something larger going longer distances, you might want to know a little bit longer forecast, um, but that's still, of course, weather at that point.
The other one is aeronomy. Aeronomy, if for some reason you felt the need of studying the higher atmosphere, uh, let's say if you work for, you know, an aerospace firm and you need to make sure that the astronauts know know what the weather is where they're going to be located, uh, usually this study of the atmosphere, uh, starts around 327,000 ft, which is just a just a little bit higher than what we can fly our aircraft at at this point. But of course, if you're in the space industry, that's not an issue, right? So it's aeronomy, very interesting, but and then, of course, last but not least, of course, is meteorology. It's something that we all have to deal with whether we're pilots or not, uh, because it's just weather quite simply, uh, it's the lower parts of the atmosphere which we'll see broken out here in a second, under 36,000 ft and in the tropopause, that's usually where most of our weather takes place, and therefore that's kind of where meteorology is focused on, uh, when we start to talk about it, we'll we'll start to include other parts of the atmosphere, uh, as we look into it. We'll see that today, um, but for the most part, uh, weather that concerns us as pilots will be located in the troposphere, with the lower parts of the atmosphere. All right, so, uh, the big issue at this point is where does our weather come from and what causes it, right? So I picked this picture because it seemed to kind of encompass all the different things that we're going to be looking at in this class. So the sun and heat exchange, which is super important, uh, since I do mention it up front, um, the sun is is the driver of the majority of the weather, uh, on Earth, and it's as it gives us energy, uh, from well as the energy comes in from the sun, it starts to interact with our atmosphere, the surface, and the atmosphere above it, uh, to start to create things like this huge thunderstorm that you see in front of us with this cool lightning, uh, all of which you will talk about during this class, and of course, it has everything to do with heat exchange because that's why that thunderstorm exists is because of a heat exchange.
Other things we'll talk about, of course, is moisture, which you can see here, uh, usually in terms of water vapor and how it interacts with the atmosphere as we go along, uh, pressure. Pressure is super important. So as we look at different pressures, uh, we get a lot of weather based upon pressure. So you have high pressures, low pressures, uh, gradients, and all that kind of stuff which are going going to be talking about, which is usually related to things like this, which is wind. So wind, if you remember, of course, from the first lecture, we talked about how dangerous it could potentially be for pilots, uh, in terms of accidents, generally speaking. As you get better and better as an aviator, as you start to go through your instrument rating and your commercial and stuff, you'll get better and better at dealing with wind, uh, based upon the, you know, the limitations of your aircraft, right? Uh, and also hopefully you'll get respectful judgment in saying I can't land at this airport, um, so I got a lot of stories to share when it comes to that kind of stuff, to give you an example, examples that you can kind of relate to, uh, if not now you will later, which would be kind of nice. Uh, other things, of course, we talked about larger air masses, of course, we'll talk about warm and cold fronts, um, and the important things about warm and cold fronts is the weather that's associated with them and the importance of being able to bestow upon your designated examiner your brilliance when they say what kind of weather is associated with a cold front, and you'll go I got this. So that's kind of nice, and that's the whole idea here, uh, in this class is to be able to help you, uh, make it through not only those but do well on the written exam too, um, at least the meteorology section. That's all I could really help you with in this class, uh, but as far as the primary driver of the energy or the weather, uh, in the world, of course, on our globe, we have the sun. So, uh, because of all that electromagnetic energy that we get from the sun, uh, it comes to us in, uh, like three, we're going to only talk about three different ways, uh, which are the majority of the ways that we receive some of that energy. So, uh, light is, of course, visible light that we see day versus night, uh, it's it's easy to understand. Ultraviolet light, of course, we can't see it unless we have like, you know, special devices to be able to see it, uh, but our biggest concern, uh, personally, is usually whether or not we're going to get a sunburn and to make sure we have enough sunscreen to be able to put on to avoid damaging our skin, especially in Southern California if we go to the beach and stuff. So, uh, but ultraviolet light plays a big role, uh, on Earth, which is nice. Infrared energy, of course, is, uh, really important also, uh, it's essentially that same kind of energy if you want to relate it to like when you go out to eat and it's kind of chilly on the patio and they fire up the, uh, the heating lamps, that's infrared energy. So, uh, you I'll use an example a little bit later on when it comes to pressures and stuff like that, uh, sitting around, uh, let's say a campfire or a bonfire down at the beach or something like that, that heat that you feel is the infrared energy. So, uh, the nice thing about that is that, uh, because of this energy exchange, we get a lot of movement in the atmosphere because of it, and unfortunately, it also causes stuff like turbulence, which is kind of annoying on really hot days if you're flying to Vegas.
But to give you a little bit more, a little bit more of an appreciation of what the sun does for us, I have a short video, uh, that I show on the sun by someone's probably more qualified to talk about the sun itself, uh, through via National Geographic. So they have this cool little video on it, so I'll go ahead and play that and we'll talk about the rest in a minute.
"While billions of stars are scattered throughout the Universe, the one at the center of our solar system plays a special role for us here on Earth. Our sun formed about 4.5 billion years ago in the Milky Way galaxy's Orion spur. It was born when a cloud of dust and gas known as a solar nebula collapsed, and in the middle of this formation, matter condensed into a burning ball of gas that became our sun. The sun's fiery nature, along with a tremendous gravitational pull and an extensive magnetic field, helped it to become the heart of our solar system. The sun can be divided into six layers or regions: the corona, the chromosphere, the photosphere, the convective and radiative zones, and the core. In terms of atom count, the sun is about 91% hydrogen, the sun's fuel, 88.9% helium, and .1% heavier elements such as carbon and nitrogen. Due to the sun's extreme temperatures, these elements stay in a gas-like phase called plasma. In the core, temperatures reaching at least 27 million degrees Fahrenheit, combined with the sun's powerful gravity, fuse together hydrogen molecules to create helium, called thermonuclear fusion. This releases an enormous amount of energy in the form of radiation, electricity, solar wind, and, as we experience on Earth, life-giving heat and light. Such volatility is contained thanks to the sun's tremendous gravity. It's strong enough to hold the solar system intact and is primarily due to the sun's size and mass. Our sun is the largest and most massive object in the solar system. It's more than 100 Earths wide and could theoretically fit all eight planets inside nearly 600 times. It also contains approximately 99.8% of all the mass in the solar system. Because of this mass, the sun has a great pull on the fabric of space, creating a gravitational force that causes nearby planetary bodies to be drawn toward it. This gravitational pull allows the sun to hold together a system of eight planets, potentially dozens of dwarf planets, at least 170 moons, and countless comets and asteroids. Without the Sun's gravity, these celestial bodies would drift off into deep space. Another critical property of the sun is its magnetic field, which encapsulates the entire solar system, called the heliosphere. This force field protects the planets from harmful cosmic radiation. It's caused by the sun's plasma pushing electrically charged particles toward the stars' poles. This process turns the sun into a giant magnet. Although the sun's magnetic field is invisible to the naked eye, its effects are noticeable on the sun's surface as dark areas called sunspots, which mark strong pockets of magnetism. On Earth and on some of the other planets, the sun's magnetic field interacts with their atmospheres, resulting in beautiful auroras. Despite its size and strength, the sun will not last forever. In about 6.5 billion years, it will run out of its hydrogen fuel, expand to envelop Mercury, Venus, and even Earth, and then collapse into a small star known as a white dwarf. In the meantime, the sun will continue to play a critical role in the system that bears its name. The sun's protective magnetic field, tremendous gravitational pull, and ability to create vast amounts of energy will protect, contain, and give life to our solar system."
In this slide, it's pretty easy to explain. You can obviously see the sun, uh, which is very important to the existence of us, uh, but you can see the little white lines that go around the earth, uh, those are the solar winds. As you get closer towards the Earth, you can see that magenta kind of dome-looking thing, uh, that's kind of the extent of our, uh, magnetic, uh, shield or or protection that we receive from the Earth. So like the sun that has, uh, its magnetoshere, uh, we have something similar to that on Earth caused by the molten core. As we spin around, it creates this magnetism. Of course, some of that magnetism, of course, we use when we fly our aircraft, right? When we use a compass, um, but in this case, it's shown by the the blue area, uh, is the area of the magnetism, and it shows those two little gaps you see kind of on the north or south or the top or bottom of that little blue area, and that's usually where most of the energy has an opportunity to get and interact with our atmosphere and create those auroras. Moving past that, the only other thing that's on this slide, which is important especially to us as aviators, is that big yellow banana-looking thing, uh, that big yellow banana thing is a solar flare or it represents what a solar flare would be, and it's when the sun emits a a bunch of electromechanical energy all at the same time and it kind of goes towards the Earth or bombards the Earth with a bunch of energy, uh, at a certain frequency. And the importance for that, uh, and understanding that in terms of aviators are concerned is our avionics. So a couple of years ago, there was a solar flare, and there are folks that actually look at the sun all the time and monitor the sun specifically for this, this kind of event, and when this event happens, and when it happened a couple years ago, what it had done is it was at just the right frequency to interfere with a particular jet's avionics suite, or or package that had in the aircraft, and they actually had to ground those aircraft for a couple of days as the energy passed by the Earth, uh, which is pretty wild to think about.
So here I have a handy-dandy slide which you'll probably find in your book, uh, which kind of breaks apart how the energy gets through, uh, our protective area, uh, and through our atmosphere and what happens to that energy as it, uh, as it interacts with with our atmosphere. So the first one, uh, or number one shows how that energy or part of the energy, um, what does it say? 19% interacts with the upper atmosphere, uh, and just kind of hangs out there. Just so that energy gets absorbed by the atmosphere at that level, uh, number two, which is that largest area, is what gets through and starts to heat the ground, uh, in our case, which creates radiating heat which creates some of the weather that we have, and then the last two, or I'm sorry, the last three, 3, 4, and 5, are called albedo, or albedo, and what that does is that's either reflected off the surface or reflected off clouds or somehow bounces back towards where it originally came from. But remember that some of it, even though it gets reflected back to its original source, uh, it will still get stuck within the atmosphere as it tries to escape, right? And we'll talk about how that happens, uh, here in a second, which you might get you might might be familiar with, uh, as we go through this course. You're going to need to know, uh, a few terms, so I'll list four of them here, and your understanding of these terms, uh, if you get very comfortable with them, will help you, uh, really kind of absorb some of the other ideas that we're going to talk about as we get as we kind of move along through the semester. So, um, this is all about heat and energy, and the first thing that we're going to talk about these four different ways is conduction. So conduction is a fairly simple concept to understand. The old-school way of teaching it was just if you had a hot, you know, a hot cup of tea or coffee or something like that, or, you know, soup, you put a spoon in it, and then you wait a few minutes, and then you go to touch the spoon, the spoon will either be warm or hot, or unfortunately, if you have a metal, you know, spoon in boiling water, uh, hopefully you don't burn yourself. So, uh, but that heat, even though that part of the spoon is not actually touching, um, the the water or whatever is is hot, uh, it conducts it up through the spoon, and that's where you feel the heat from. So it's just a transfer of energy, and you're going to start to see that, uh, in different ways, uh, in the atmosphere, such as the transfer of energy from the surface into the atmosphere as it radiates back up. We're going to talk about convection. This is huge. So this is that vertical movement of the air, uh, so think thunderstorms is probably the easiest way to remember, and we'll talk about what convection is, how it works, and, uh, how it affects, uh, the, you know, especially during the summer months, monsoon season right now, uh, uh, is is pretty amazing. So we'll see how convection works. We'll talk about advection a little bit later, but just remember it's that horizontal movement of air or an air mass which usually, uh, contains moisture or some kind of visible moisture. Uh, evaporation is a pretty simple process, right? So if you have like a glass of water and and you know you have condensation that builds up on the outside, if you leave it out there long enough, it starts to warm, and all of a sudden, all that, you know, wet condensation off the side disappears, and as it disappears, your drink gets warmer. So drink your drink before…
Before the water disappears, the earth's atmosphere—of course, we touched on what this picture was—and, uh, so keep this in mind as we start to talk about the atmosphere. When we talk about the atmosphere, we're going to be focusing on things called parcels. Parcels are kind of an imaginary body of air. And with that imaginary body of air, we can we can put different components within it, right? So we can add temperature, we can take temperature away, we can add moisture, pressure, and all sorts of stuff, right. Um, so this is a pretty pretty basic picture here, and it shows different parcels in different stages or composed of different uh things, uh, which we'll use to give examples and help you understand how things work, uh, which is nice. So that is one of the biggest components that we use as we go through the class.
But in order to understand, before we start to talk about the parcels, we need to understand what our atmosphere is made up of. So, the atmosphere is primarily gases, and you can see them listed in the picture on the right-hand side. Uh, the first one, of course, which is the largest, is nitrogen. Nitrogen is important, of course, for the development of proteins and, of course, ourselves; that's kind of important, right? And so therefore, it's the biggest uh gas that is contained within our atmosphere, as you can tell just by looking at the picture. The next one, uh, out of a scale of 100, as you can see, we're chopping away at it pretty quick, is oxygen. And oxygen is pretty—everybody's fairly familiar with oxygen—that it's kind of an important thing to have in our atmosphere because that's what we need to live uh on Earth and at our surface of 14.7 PSI. Our bodies are used to a certain amount uh of oxygen based upon the pressures in which we live. Um, and we'll talk about that as far as like altitudes and stuff a little bit later. But oxygen is 20.9%, and uh, the amazing thing is we've almost—we're getting pretty close to 100% already—so what's left is argon. Argon's kind of a cool gas where—uh, actually not cool as far as temperature, it's just kind of a neat gas because it doesn't interact with anything; so it's an inert gas. Uh, the nice thing about uh argon is how you can use it. If you can separate it out and use it in like industry, you use it for like welding. Uh, when you use it in welding, normally uh when you weld certain things like titanium and aluminum and stuff like that, you don't want any oxygen uh there when you start to weld these items together uh because it causes splattering and kind of crappy welds, right? So to avoid that and get rid of the oxygen while you're welding, they have tanks of argon gas that push and basically replace the the atmosphere around where the welds are happening with argon, which does not interfere with the welding itself, so they can make really—and of course, gets rid of the oxygen. Other places—common things that you'll you'll see argon gas used—is in double-paned glass uh in in your house. So if there's gas uh between those two panes, it's used because it doesn't interact with anything; it's a great insulator. So that's another industry-wide use of argon, and that's .9%, not even 1% uh of our atmosphere.
So you're thinking, "Has something missing here?" Well, carbon dioxide, right? That's always in the news; we're always talking about that one. And uh, in this case, carbon dioxide only takes 0.3%. So anyway, so the nice thing about carbon dioxide in the terms that we're going to be using in our class is carbon dioxide has the ability of—of keeping our earth warm. Now that's actually a good thing. Uh, too warm and too cold are different stories; that's for a different class. But in our case, understanding what carbon dioxide does in our atmosphere is actually a positive thing. So when the energy comes and hits the surface or interacts with our atmosphere and tries to escape, carbon dioxide has the ability of keeping some of that or retaining some of that heat, which is great because that's what keeps essentially the world a little bit more temperate uh and allows life to continue to exist. And because it interacts uh with, of course, plants and and other organisms such as diatoms and stuff in the ocean uh it creates oxygen, so it all kind of works together in a big process, which is is which is great. Other gases, of course—whatever's left over, right?—we'll just throw it in the other gases because we don't want to get too technical in this class, um, but I'm sure there's something probably pretty interesting in that. But other than that, there are two other components that are important for us as pilots to understand that it's in the atmosphere: water vapor. So water vapor, at its lowest level, no matter where you are on the earth, I think it—the only thing it—it drops as low as like 4%, I think that's the lowest uh amount of water vapor that has contained, you know, as you go around the globe and try to measure it. Uh, that's what I've—the research I found because I was always curious: is there is there an area that like doesn't have any water vapor, like some desert or something? And I was really surprised to find out, well, that's not the case; it's it's always there in one way or another. Water vapor, of course, is important for us to understand because that's where we get clouds. But in order to get clouds and to be able to see the clouds, uh, the water vapor needs something to kind kind of attach itself to, and we'll show that when we get into clouds. I'll show you a video how that works. But uh, to attach to something, we need particulates in the atmosphere. So particulates are aerosols—anything that's contained within the atmosphere and where water vapor can attach itself to to create clouds. Uh, it happens mainly because there's a bunch of particulates that we can't see uh that are always there in our atmosphere uh so we don't really have to worry about that. Um, but uh, prot—so if you're trying to think of like, "Well, give me an example of what a particulate is," think of like uh salt from sea breezes, you know, like the ocean; think Santa Ana winds and all the dirt that's kind of blown up, or just wind on a daily basis, right? So I—you think about it—the wind's blowing around, and there's dust on your plants, on the ground, in the area; things just get moved around, and so it uh, you know, it's a good thing. So and we and we'll see it actually happen uh in a little experiment that I'll show you a little bit later, which is kind of—not today—but we talk about clouds.
All right, so now we understand what makes our atmosphere or what's contained within our atmosphere; we need to now understand the layers of our atmosphere, right? So I had talked about earlier a little bit about the troposphere and the stratosphere. I might have mentioned the stratosphere; if not, you'll know now. Uh, the troposphere uh in this case is shown from the surface to 36,000 ft. Just a reminder that this is nature, so when we start talking about some of this stuff, uh there is variability associated with it, so it's not an exact number; so it's a range. And this number 36,000 ft is an average. So from the uh the surface to 36,000 ft is where the troposphere is located, and I'll show you in the next slide why this actually can vary in altitude uh based on based on the density of air. But when the troposphere—where most of our weather takes place and most of us flying—it's important for us to truly understand uh how this kind of layer of the cake works. So as we start to talk about these different ones, think of each layer as a cake. We're not talking about airspace if you're working on airspace, but think of the cake as the majority of—in this case, like the troposphere—and then above the troposphere, in between the stratosphere or the troposphere and the stratosphere, will be a tropopause, right? Think of the tropopause is like the icing of the the cakes in between, right? And the reason why I like to use that example is because icing is a separation between one and another, right? And there is a period or an area between these two where things don't change, and it'll make sense when you see the visual on it here in a second. So the first thing we're going to talk about, of course, the troposphere. Uh, if you look at the example on the right-hand side in the picture, as you'll see the jet aircraft, but the jet aircraft is not flying in the troposphere; it's flying in the stratosphere. So sounds pretty cool. Stratosphere: 36,000 to 160,000 ft; it's quite large uh and really high, right? So uh most of the time when you fly in an aircraft, uh you're going to be most likely flying in the 30s somewhere; could be the low 30s where you're in the tropopause, or it could be in the mid 30s, like 36,000 ft or a little bit higher, like 38, 39, and some of the biz jets will go up to about 50,000 ft. So the stratosphere—there's a good reason for it—as we show you in the next slide uh you'll see why the stratosphere is important for aviation and why that aircraft is located in the stratosphere. The next one is the mesosphere: 160 to 280,000 ft. Uh, the interesting part about this one is this is where—as you can tell by the slide—where most of the meteor showers will happen. So when you see meteors—when we look up in the sky, like in the desert or where there's less like like light pollution—we kind of—out of the city—and we can see the stars, um, if you get to see or get the opportunity to see some meteors, which is cool, it's at this altitude you actually see them starting to burn up as it cruises through our atmosphere. Uh, the last one, of course, we'll talk about is uh the thermosphere. Thermosphere: 280 to 550,000 feet; it's a little higher than we're going to fly, so we won't focus too much on it, but it just—you need to understand what those four layers are. Why? Because we can—not necessarily in my class, even though I think you will—get it; that is a test question. And the only reason why I know it's a test question is because I have highlighted all the words in blue. There's your little foot-stop and little tip uh as far as this class goes: if it's in blue, you're probably going to see it again somewhere. So uh there are other parts of the atmosphere uh such as the exosphere where all the satellites are located and stuff; we're not flying up there, so I mean even the shuttle didn't fly up there and it had wings, right? So we don't have to worry about that as much, but just need to understand that it's there and what is contained within it, uh which is pretty interesting. So can anybody tell me what the significance is? I'm just curious to know if you know what the Kármán line is. So if you fly above the Kármán line, you're not a pilot anymore; you're an astronaut.
The next thing we're going to talk about, of course, is why the layers of cake are different from each other. Uh, you'll see this also in your book as it starts to talk about uh the different layers are—the one we're of course spending most of our time with in this class will be the tropopause down at the bottom. Uh, the nice thing about the tropopause is the consistency in which the temperature decreases as it goes up in altitude. So you can see that kind of straight line; that straight line is equivalent to—and if you have something to write down, just give it to you early though, we'll talk about it later—um, that that line or gradient is 2 degrees Celsius per 1,000 feet. It's also called a lapse rate, which we also will talk about later. It's not important for you to know it now, but it will be important for you to know later, so I'm also just give it to you now: so 2 degrees Celsius per 1,000 ft. So every time you go up 1,000 ft, technically the temperature should drop 2° C. Does it always? Well, it's Mother Nature, right? So no, it doesn't always, but as far as the FAA is concerned, that's the number you need to memorize because that will be on the test—mine and the FAA's anyway—we'll kind of beat that one up a little bit later, but you'll see it's very consistent as it goes up to the tropopause. A change happens in the temperature. So we consistently went down, down in temperatures until we hit the tropopause, and then there's that area uh where it transitions to the stratosphere where, as you can tell, it just goes straight up; in other words, there's no change in the temperature as you go from one kind of cake at the bottom to the next one in that icing area. Uh, and in the case of the stratosphere, the temperatures actually start to get warmer. And as we'll find out a little bit later in the semester, that when things get warmer in the atmosphere, it creates—in in this case, it'll create more stability—and how you can visually see that stability is via a thunderstorm. If you've ever seen a thunderstorm uh that you know grows, it gets bigger, and then it creates that anvil that comes off the top, and then the anvil kind of points in the direction of the relative wind, but it's that flattening of the thunderstorm—that's where it's getting warmer; that's the stratosphere—and that's where the temperatures don't change as much, which is what you need to continue to build that energy in the thunderstorm. Uh, if there's not as much temperature change, it just kind of stops. And uh, that's the reason why that jet was flying in the stratosphere is because it's more stable as far as the atmosphere is concerned because at that point it starts to warm. So it continues to go up in the mesosphere and thermosphere; of course, we're not flying at that—on those heights—but you still need to understand what those are. Uh, the easiest way to remember it is we know the temperature drops consistently because we've memorized our lapse rate uh in the troposphere, so it gets cold, colder, warmer, colder, and warmer. So if that helps you remember what happens as you get through these different layers, uh just use it for what it's worth. All right. On the right-hand side, you can see a picture of the globe, of course; it's not on its 23 and a half degree, you know, tilt in this picture, but you can see the different layers, and in this case, you can see that the tropopause uh is egg-shaped. And getting back to what I talked about earlier as far as the density of the air, that's the reason why it's shaped that way. So on the poles, where it's colder—colder air is more dense—so as far as the altitude that the tropopause will be at, it will be lower because it'll be a little bit more compacted, right? And it's the uh the equator where it's warmer—the air will start to expand, or the atmosphere will expand, or more specifically, sorry, would be the tropopause will expand uh at the equator—and that'll have a lot to do with when we talk about global circulation and stuff later. But remember, uh, as far as the altitude that you'll find the tropopause, it will be different between the poles and the equator. I'm just setting you up so you are successful because we're going to talk about this later. All right.
Other concepts you guys need to understand are uh fun science ones, right? So we have temperature, pressure, and density. So the first one we're going to talk about is temperature. So in this example, we have two different parcels. So here we get the opportunity to talk about parcels. They're both exactly the same except for their temperature. Temperature is a measurement, of course, is the energy, or it's a measurement of the energy contained within that parcel. So if you put a thermometer in it, that thermometer actually measures energy, and the more energy something has, the warmer its temperature, or that tactile temperature that we get um what that we equate with warmth or, you know, warm and cold, that kind of stuff. In this case, with these two parcels of air, we have the exact same number of molecules contained within it, and in the one on the left-hand side, it's cooler, and because it's cooler, it has less kinetic energy, or I should say it almost works better to say because it has less kinetic energy, it is cooler. Now, on the right-hand side, of course, we have more kinetic energy, and the molecules are more excited; you can tell they're kind of whipping around in that space, and therefore the temperature is warmer. So temperature is a big component, and it interacts—probably one of the biggest things that interacts with our atmosphere—and what you need to be cognizant of when you do uh a lot of your performance, and we'll talk about that and as it relates to like high-density altitudes a little bit later. Talk about density here in a second. So the first one's temperature, right? The second one is density. And density—there's four different parcels of air in this picture—you see the ones on the left-hand side uh are both exactly the same, and then on the right-hand side, one is the same size cube and one's a much larger cube. So to compare the two, in order to go from a high density to a lower density, you can do a couple of things, right? Uh, the first example, of course, is to show that if you remove the one at the top—if you remove some of the the molecules that are contained within that parcel—it will be less dense; there's just less stuff in that parcel. Uh, if you look at the one on the lower—if you were to keep the same number of molecules without removing anything but just make the volume of the cube bigger—it now becomes—that parcel becomes less dense because of the area the molecules are contained within. So there's two different ways you can deal with density, and don't don't forget it goes the opposite direction also, so that's the example of density. And then the last one we're going to talk about is pressure. So it starts off with that uh that parcel of air that's kind of in the center; it's kind of the benchmark that you compare the other ones too. Uh, but the difference in pressure from what we saw earlier in temperature—temperature measures what's within the parcel, right?—so that's where we're measuring the temperature with pressure. We're actually measuring the outside of the parcel. So in other words, we're measuring how—basically how hard those molecules are whacking into the side of that parcel—and it gives us kind of a reading of how much pressure is contained with within uh that parcel. Think like a scuba tank, or if you fill up a tank, you know, you'll be able to feel more pressure. So in this case, we start off with the one in the middle, and then we notice as we start to cool it and that kinetic energy slows down, the molecules will essentially hit the sides of your parcel less, and therefore your pressure inside that parcel will decrease. If you go into the middle—similar to what we saw before—but this—in this case, of course, it's pressure—if you remove uh half the molecules but keep the energy level or the same kinetic energy, you'll still reduce the pressure because there's just less molecules or mass inside the parcel to create a higher pressure. So you lower the pressure by reducing the number of molecules. And then, of course, the last one—similar, of course, is what we saw earlier—if you increase the volume of the parcel of air, uh it has longer to travel from the molecules to hit the side; that's just a bigger area, and therefore you also get less pressure associated with it. So it's important to understand to keep all three of these separate. So when you're looking at uh when you're looking at uh like a performance problem that you're eventually going to work on, uh you you'll find out as you look through the performance charts it takes—separate the pressure like the standard pressure versus the temperature—so you have to actually look at each one separately, even though they kind of interact with each other to cause a change in performance of your aircraft, you need to understand that they are actually different from each other. Um, the International Civil Aviation Organization—this is a global organization, as you can tell—it was formed back in 1919. Remember, we only started flying in 1903, so things started happening pretty darn quick, and these guys wanted to get their hat in the ring, right?
Away, and make sure that there are standards which all of us will then use going forward, uh, to make sure there's consistency. So whether you know something's made in America, or it's made in Europe, or Germany, or or whoever else, in Brazil, or wherever else they want to make the aircraft—Canadians, I believe—there's enough. Um, the whole idea, of course, is to create those standards which we all kind of, uh, you know, know, except as the benchmarks. And therefore, in aviation, we memorize some of those in order to compare whatever the existing environment is that we're flying in that day to whatever these benchmarks are, because the aircraft is created based upon numbers, uh, such as the temperature and pressures, that kind of stuff. And then, of course, when we fly, well, the temperature that day could be warmer or colder, as an example, from what when they actually created this aircraft, right? So we need to keep that in mind, and that's why we learn all these numbers.
So, uh, FYI, stuff down at the bottom is they created certifications for meteorologists and other kinds of stuff, uh, but interesting organization. You'll hear a little bit more; there's about 188 countries that are associated with this, and so most, most of the developed nations are on board, uh, uh, to make sure that there's consistency. Like if we go to fly over to Europe, or they come to fly over from Europe to here, uh, everything will be they, they'll know what to expect, so no surprises. I can't imagine if everybody had different rules for stuff, and it's like, well, we use this number for our standard temperature; it's like I would just drive everybody insane. You'd have to have all the—I don't think about it; my head hurts. So anyway, to define how uh the AO uh uses this information, they create what's called an ISA, or it's the international standard atmosphere; it's a hypothetical model. And in this particular case, just like I talked about earlier about parcels of air, where it's just kind of made up, and it's made up of whatever you define it as, right? So here's how they define uh the international standard atmosphere; so it's ideal in their case, and it was created by them, of course, that everybody—I'm sure they all sat around in a meeting at one time and said, "This is the numbers we want to use," right? It is devoid, in this case, uh, when you look at the ISA, uh, of water vapor, wind, and turbulence, because you don't want any of that variability associated with it. All right, and we can see the different items that they talk about, which is what we kind of talked about earlier, which is pressure, density; we will talk about viscosity, which is pretty important; and, of course, temperature, temperature being a really big thing. So just keep an eye on this; um, you'll find later on, as you start to fly bigger, faster stuff, you'll use the ISA; there's charts, uh, and as you fly the aircraft, if you're trying to figure out it's like, you know, "Why are we burning more fuel than anticipated?" Then you take a look at the ISA chart to see, you know, like a quick reference, unless you want to use a calculator, of what the international temperature, you know, the ISA uh temperature at the altitude you're flying at. You go, "Oh, it's warmer up here; that's why we're burning more fuel," that kind of stuff. So it's actually pretty useful stuff. All right.
Um, so that's the uh the ISA. We'll be referencing this throughout the semester, so it's important for you to understand what it is and why it exists. Uh, the first thing we're going to talk about, because it's probably one of the biggest components as far as aircraft performance, uh, is temperature. And you'll see like when we calculate different things, when you do it in either Stanley's class or my class, uh, you'll use standard temperatures to do a comparison to whatever the existing temperatures are in, in the environment that surrounds you. So what are the standard temperatures? Of course, is right here in blue. Here's your hint: 15 degrees Celsius and 59 degrees Fahrenheit. I only give you Fahrenheit because the FAA loves to cause pain to your brain, and uh, unfortunately, sometimes they throw Fahrenheit and stuff. Please be careful when you're taking the test and make sure that you understand whether or not whatever they give you is in either Fahrenheit or Celsius. All right, when you get out in the real world, we all use Celsius, period. That's all we use. Uh, the only reason why you need to understand the other one is just in case you're like somewhere else, right, and that somewhere else doesn't have an ATIS or some way for you to get the weather information, and you, but you have a thermometer, or you're using your iPhone, which is not really a good choice, but it's better than nothing, uh, to figure out what the temperature is in the area that you're at. And uh, most likely it will be in, in, in Fahrenheit. The nice thing about the iPhone or your Droid or whatever you're using is, of course, you can switch that to Celsius, so keep that in mind. Otherwise, there's calculations to go ahead and do the conversions, but 15 degrees Celsius is a huge one; it's sea level temperature, and it's a standard that we use in aviation on a regular basis. You'll see it used quite a bit in this class, so memorize these bad boys, right.
Uh, let's see. So the next thing we'll talk about, uh, now that you guys are, are busy memorizing these two little factoids, is heat capacity. So heat capacity and terrestrial radiation. So whenever all that energy comes from the Sun and hits our surface, whether the surface is, let's say, land versus the surface is water, uh, different things happen to that energy when it hits different substances. Okay, so uh I use the definition—this one's pretty straightforward—here's a quote that actually tells you exactly uh what the heat capacity is, and I'll show you a graphic here in a second that talks about, or it actually shows uh where two different substance, substances are heated up; uh, the one that's a little bit more stubborn, uh, we have to wait for that one to heat up, that one gram of substance to go up that one degree Celsius before we can do a comparison with the other substance. So if you want to guess which one absorbs more energy versus the other, of course you can look at these two next factoids. Solid surface, of course, takes it in and releases it faster, and a liquid surface, like the ocean, of course, takes it in and holds it, uh, similar to like a battery, where it takes that energy in, holds on to it, and then as things cool off around it and it starts to release that energy, it creates a consistency, uh, similar to our climate. Here's our climate, which is unique; it's kind of Mediterranean, and it's fairly consistent for the most part. Uh, places with water, a little bit more temperate and consistent versus the desert, where there's more volatility associated with it. So an example that I throw out uh as far as understanding uh like this concept of heat capacity and terrestrial radiation is, is the beach. So you drive into a parking lot, your parking car, you hop out, you start walking towards the beach. Now you have some friends that are closer to the ocean, so you have this large expanse—think like Huntington Beach—large expanse of sand on a very hot day, and you have to walk without your flip-flops, and you have to get to those folks on the other side, but you know when you get about halfway your feet are going to be on fire. So what can you do if your heater's on fire? Heat's on fire, and there's no trash can with a, with a shadow, or someone's umbrella; there's nothing. What do you do with your feet in order to cool them off, in order to continue your quest to get to your, your friends that are on the ocean side? Dig your feet in deeper. It's pretty—it's, it's nice because uh when you dig your feet in, all of a sudden it just, it's cool right underneath the surface. Like that's, that's kind of weird; why isn't like all the sand uh warm or, or hot? And it's because of its heat capacity, its ability to hold heat in before releasing it as radiant uh energy, right?
So to show you what that looks like, of course, is this fabulous graphic that comes from Gleim. If you use that to study for your all your, you know, your private, instrument, commercial, that kind of stuff, uh, I, I've used them in the past; work pretty good. Uh, this graphic I like quite a bit though, because it's like really kind of straightforward. So if you look at them as kind of like columns, on the left column on the left-hand side, you, uh, you have two items, so you have uh water and sand that are comparing against each other; they're both the exact same quantity uh based upon what substance is in the container, right? They're both exactly the same temperature, so everything is the same on the left-hand side. Uh, you fire up the, the, that the candles to go ahead and add heat to the system, and then you just hang out. So you have, let's say you can't see it, but let's say you had a temperature probe in each one of them, and you wait for the last one, whoever's the slowest to go up at least 1° C, and then we're going to compare the two. So water, of course, takes the longest, and therefore when it goes up that one degree Celsius, which is what we're looking for, we move over to the right-hand side and we look at the two items, and the sand that we were originally talking about uh does go up quite a bit, but we know as, you know, running across the sand, if we dig our feet down it's a lot cooler. Of course, we're heated from the bottom, so it doesn't count in this particular case, but uh we can tell the differences between the two, because for some reason the water didn't increase in temperature as fast as the sand. All right.
Um, how does that work, and why does it work? Is it has everything to do with its, is with water's ability to retain its heat capacity. So roll on into the next slide, which we talk about heat capacity and water. So knowing that sand is going to absorb that energy uh to a certain point and just turn around and release it, right, almost like reflection, but not exactly, because your feet are still going to burn on the top of the sand, so it's still going to hold some of it, but it's not going to go as deep, right? So the heat capacity of water is interesting. Um, water is unique because it has the highest heat capacity of a liquid, and this is how it works. So all the energy from the Sun comes in and it hits the water, the surface of the water. As it starts to do that, uh a reaction starts to happen in the water, so those little water molecules inside, which of course we can't see, have these little hydrogen bonds that aren't connecting those molecules, but they're attracting the molecules to each other with these bonds. Well, when the energy goes in the water, it breaks those bonds, and as it breaks those bonds, those molecules now free to move about anywhere they want to go, and uh they're happy, so it'll keep absorbing the energy and breaking these bonds further and further uh uh into the water, or deeper into the water, uh as long as it's exposed to the Sun. So in this case, like an example I use, if you're a snorkel and you go out and you're having a good time looking at whatever's below you, and you see, "Oh, I want to see; there's a shell or something I want to look at," and you go to dive down underneath the water, well, when you get to a certain point you'll notice that there's a difference in temperature between the surface water and below. You'll hit what's called a thermocline, and it gets much cooler as you start to dive down. Sometimes it's, it's pretty big, and you get really chilly as you continue to dive down. I don't know if anybody's experienced that before, but it's a, it's, it's kind of cool when it happens, and this is the reason why it happens. So in this case, as it continues to uh heat up until the sun goes down, and then as it starts to cool off, this is the, this is the neat thing; this is what makes temperate uh climates like uh where we are in Southern California, similar like Italy and stuff. So when this happens, now those bonds will start to reform, and as they start to reform as the water cools off, it releases the heat energy that it was absorbing during the day into the atmosphere. And that's why when you live close to water sources, there's a little bit more consistency to the temperature surrounding that area, and it's because of the water and its ability, or its, its heat capacity. The other bonus, of course, is us, right? So we're, we're mainly made up of water, and uh so we get to take advantage of this uh this concept also, so which is why we don't start boiling on super hot days; we just end up sweating, right? And uh anyway, so there's uh heat capacity and water. Hopefully you understand that a little bit better. Well, if not, I'm going to keep going, and got a couple slides left, but first, before we get to the next slide, you just need to understand that this was going to be a video, and this transition I'm making here is so that we understand a little bit more about uh the equinoxes and solstices, if you guys have ever heard of those before. Uh, that's the interesting thing: as the Earth rotates around the Sun, and because we're on an angle of 23 and a half degrees, the, the amount of energy we receive from the Sun uh at certain points can be equally the same—Equinox—and then other parts of the year, of course, we're, we're slanted away or towards the Sun, as it'll explain in the video. So I don't want to have to repeat exactly what the video is going to teach you; um, it'll create like winter and summer, but the important thing for you to understand as, as a pilot is that, that with the Equinox part, right? So we're getting uh we're right around one of those equinoxes where uh in this case is fall, uh fall versus spring, and because the, the energy from the Sun hits that part of the globe kind of equally uh for the most part, we actually get more volatility or differences in our weather, instead of being hot all the time or cold and rainy all the time; it's more consistent uh that we get different types of weather during fall and spring. So doesn't necessarily show in Southern California, but it does in the Midwest. So think about uh uh you know, like tornadoes and big storms. I think of the weather that you just kind of look across a globe and look at the big picture of the United States, and you'll start to see how we get a little bit more weirder weather during fall and spring. So I'll go ahead and set this up and uh turn on this video and learn a little bit more about it. It does stop abruptly; sorry about that, but I know you guys don't want to hear ads. I don't, for sure. You know that Earth orbits the Sun, right? And that it takes a full year for our planet to complete its orbit. Earth also rotates like a slightly tilted spinning top. Earth remains tilted in the same direction all year round as we orbit the Sun, but that means the Sun's light shines differently on Earth at different times of the year. Let's look at Earth when it's winter in the northern hemisphere. Observe how the North Pole tips away from the Sun. This means that sunlight strikes the Northern Hemisphere at a shallow angle for a short period of time. This is why winter weather is generally cool, with short days and long nights. As Earth orbits the Sun, we move towards spring in the northern hemisphere. Now Earth is tilted neither toward nor away from the Sun, as day and night are about equal in length. As we, we make our way to the summer months, notice that Earth is still tilted in the same direction, only now on the other side of our orbit. The North Pole is tipping toward the Sun. Sunlight strikes the Northern Hemisphere more directly, and the Sun stays in the sky for a longer time compared to winter. Summer days are warmer, and the Sun stays in the sky much longer. Notice too that while it's summer in the northern hemisphere, it's winter in the southern hemisphere, because of Earth's tilt; the seasons are reversed. So, uh, but this is actually a pretty cool one, because uh it not only shows you the, the equinoxes and the solstices, but it'll also show you uh the dates. And the neat thing about this is if you watch some of the videos on—there are certain uh societies, like the Mayan culture and that kind of stuff, where they create whether it's uh pyramids or uh some kind of object—that during certain times of the year, it's consistently within a day or two, which, as you can see, this is exactly when an equinox or a solstice happens—um, the Sun will hit it just right, and it will, let's say, light up a room or something like that, which is pretty interesting. I think Stonehenge has that too, uh, but either way, uh the nice thing about that is, of course, in, in our case, as pilots, understanding equinoxes will give you a little bit more volatile weather, um, and, and of course, the solstices will make us either summer or winter. It also tells us, gives us a reminder of the days are getting longer or the days are getting shorter. So unfortunately, as you can see, September 22nd to 23rd is when our Equinox will happen, so pay attention to that, and uh and unfortunately, as we already probably can tell now that our days are thinking about getting a little bit shorter, it's not staying light till 8 o'clock at night, and of course it's just going to get less and less sunlight as we get into winter. Uh, but the positive thing is if you're flying, you can get all your night flying done and get current, which is nice. All right, so at that point, I'll leave you with the good news that you can get current night flying if you're flying during the winter season and set you up to be, be successful when we start talking about pressure next week.