Hello and welcome to another lecture of introduction to virtualization course My name is Jetta jar. So, in this lecture, we will make an introduction to aviation mythology. So, let's right dive in on our agenda today, we will talk about what is mythology, it can position of the atmosphere and the notion of visibility, the some of the cloud types, which I hope you will find very interesting, and some of the weather events that could have impact or that have impact on the procedure and working of aviation, and you can see the list here. Okay, so let's start with the question. What is mythology? So, meteorology means the study of the atmosphere and all the events that took place in But when we say the word metrology, the image or the stereotypical image that comes up to our minds is usually like this that the picture that you're seeing now, this is taken from a like a news our the weather forecast but let's just say this part this this this forecasting thing is only a part of a small subfield of metrology which is called general methodology or forecasting okay.

So, metrology is much more bigger and detailed science than this. So another example that we can take, how the how metrology is really important and how could it be really out of the box, then our conventional thinking like rain or you know, storm or other things you can see Here there is the this the the volcano that erupted in 2010. In Iceland, this volcano, that which I found its name really hard to pronounce, but I think FTL logical volcano is was erupted in 2010. Okay, so it's happened in Iceland, okay? But what happens when a volcano in this scale erupt erupts. It also fires a lot of small really really micron sized scale particles which could be seen under the microscope like this.

But as you can see they're really sharp small pieces, they can hang on the air with the help of the heat, but when they are hanging on the on the balance in the air, also they could carry it by the air masses. So this is a problem. Because when it erupted in Iceland at that year, after a one week or in a matter of weeks, did the clouds that loaded with this volcanic ash that I showed you in one slide ago, these these clouds are you know spread and distributed over the Europe. So, much of the air traffic has been affected bee bee because of this volcanic ash cloud, this is a really problem for the aviation. So, when we think about mythology, and we can think about general metrology which can make very forecasts, sometimes they are, you know, become truth. Sometimes they're not but the the the statistical percentage have really high but also for the methodology the branch off to metros which we call variation methodology.

It deals with problems like This. So we some of the things that happen in the ground in the earth can really have drastic consequences in the atmosphere. So atmosphere, as you can tell is a cultic system seems like chaotic. So it's like really hard to make models fit. Or if you do simulations, models of how would it behave after certain time, and D, the percentage of being there becoming true. Coming up true is really not so high.

So when we can take this example of volcano in Iceland, when this cloud covered the skies of the Europe, and then it also spread over, you know, eastern parts like Turkey and Russia, what happened, aircrafts couldn't take off and the ones that they're in the air should immediately land and the closest airplane airports Why? You may ask because this small volcanic ash can create high speeds like an aircraft like an airliner jet can create really big damage on the whole of the aircraft that so you can see on the left you can see that as an example. This is not this is not a an aircraft, or like an incident from the Icelandic volcano but it is because of a a volcano in the Indian Ocean. And at that time in the night, a one of the British Airways seven four sevens Boeing 740 sevens at that time also today, I think that there are there are weather radars in the cockpit so they're individual radars for airplanes.

And then these radars you can see in the in the, you know, in a range in a certain range You can see whether there are clouds or stormy clouds that that the clouds loaded with humidity. So these are one of the or ice. So these are really dangerous clouds which pilots should have to avoid. But since the volcanic ash is really dry, and it also can, as I said, hang on the air like inside of a cloud, the weather, weather radar cannot show so they are basically invisible to the weather radar. But when they are inside of this volcanic cloud, you can day see something like this shining and this sparkling all over the whole whole of the aircraft. And this is called send Alamo fire.

This incidents phenomenon called San Telmo fire, said Alamo fire so this happened so this could look look like cool and shiny but when it's landed, the real damage was can be can be visible when they Look to the engine, blades of engine, they were all melted down and sticked while canik ash there so the problem with this material is first, it's really sharp in in the high speeds is can really damage the damaged aircraft, for example the windshield of the aircraft was becoming was was basically you know blurred because of the erosion that it caused. Also for them engines when they got inside the engine and in the combustion chamber. You can remember from the aviation history course in the combustion chamber in the high and high temperature, they're becoming melted and when they are exiting the engine, they are getting cold and then sticking to the, you know, turbines and that is a huge problem for the aircraft.

Also for the incident of the British Airways flight. What happened some of the engines were stopped out of no reason, then they try to descend. So, you know, descend a little bit down. And when they did this when they get out of the without knowing, when they get out of the cloud of volcanic ash, then it just started again. So, that was a big problem two cause engines to stop because of the melting and sticking material. So, this could be an example of a a Earth, a matter can affect atmosphere in a ways that we cannot imagine.

So at that time, since this this volcanic ash was a known phenomenon from the incident of British Airways and other incidents in the recent time in 2010, the aviation authorities that we talked about the organization for example, the EAA esa Asr, or I kale band all the way across to you know, band ole aviation operations to be stopped immediately because they know this could happen and this could result really catastrophic consequences. Okay. So, when we return to Our first question, what is mythology what metrology is, by definition, the study of Earth's atmosphere. mythology is an extremely interdisciplinary science. So drawing on the laws of physics and chemistry among other scientific areas to aid in our understanding of Earth's atmosphere, its process and structure. And since we can understand it, then we can forecast and we can predict it.

Okay, so this brings us to the second part of the on our agenda, which is composition of the atmosphere. So as virtual pilots, virtual aviators, the composition of atmosphere and everything inside it is really important for us since we are flying inside it It is like if we create an A knology here, the water or the seas, the knowing the composition of the sea and how it behaves is really important for a captain of a ship. Now it's really important to know the composition and the behavior of the atmosphere to a pilot. So, this is really important composition of atmosphere by volume dry air contains mostly nitrogen, so around 78% of it contains mostly nitrogen and then the 20 or 21% is oxygen which is really vital and essential for to have life and then there are really a significant amount of oxygen and then the like really small amount of carbon dioxide and this carbon dioxide can increase and decrease sometimes, which can cause the so called sera effect, okay, so Or like the, the greenhouse effect.

So and small amount of other gases which are really, really insignificant in that amount. We don't don't go into details of that. So what we know is dry air contains mostly nitrogen, then the second come oxygen and some Argan and lastly carbon dioxide. But the thing is we call dry air you can like some of the intelligent or you know, really keen we were here can ask the question, why dry air because all of the you know, weather events are happening because of water, which we can say rain, snow and other things. So they're right air also contains a variable amount of water vapor. On average, it's around 1% at sea level, and point 4% over the entire atmosphere.

So Point 4% over the entire atmosphere is water or it's not like a like fluid water, but in a gas form so water vapor. So this is really important because this 1% at sea level or the water vapor, all of the atmospheres point 4% is the primary cause of many of the maybe almost all of the weather events and these weather events really important for us as pilots. So, this brings us to the second part of the composition, which is layers of the atmosphere. But first one thing that we need to understand really deeply A is the the, the, the the density of the atmosphere. So, the one thing the gravitational force or the gravity or of the of the Earth is stemming from its core. Right.

So stemming from its core like the core is here, so to say Okay, so, when you go far, so when you go for like, when you go farther away from the core, the gravitational force decreases exponentially, okay? So it's decreases like logarithmically. So, if, so, if you, if you for example from the source if you let's say add go farther away one x okay or like to x we can say two x k, then the amount of the gravitational force decreases is at two power to two x power, okay? So it's like exponentially, you can see. So this is really important. So when you are close to Earth in the atmosphere, The gravitational force of the air on the edge of the earth on the air molecules is really stronger.

But when you're going away, so that means gain altitude go upper and upper layers of the atmosphere, it's becoming less and less and that means for the air molecules are less attracted to the earth, and they're becoming less dense and dense. So, they are becoming a you know, scars okay. So, this is really important for us. So, one thing to know when you go down and that was fear, when you go closer come closer to the earth, the density of the air is higher and when you go high, so when you gain altitude, when you go up, the air density goes down. This is one important principle. The other thing is, you can think of this atmosphere as like an ocean.

Okay, so you This is the surface of the ocean. So, you dive in the ocean and as you go deeper and deeper the sea pressure the pressure above you is increases Why? Because when you go deeper and deeper okay the mass of the air or water like if we can talk in analogy here the water is increases. So, here you you need to carry this amount of this amount of water on top of you, but when you go deeper and deeper, the pressure increases because the amount is increases, it also increasing, you need to carry Okay, so we can think of like this. Here, let me erase them. So when you think of like this DD amount of air is also increasing when you go deeper and deeper.

So, we as humans living like here, really close to Earth. So we have one atmospheric pressure. So it can Call 180 M. Okay, so we all evolved to live under a one huge atmospheric pressure. So we carry this load, but this also has an effect when you when we go up and up, that means the air pressure decreases. Okay, so let's recap on the rules, the basic rules, and when you go higher, the density goes down and the air pressure goes down. Okay?

This is the rule, this is really important air pressure and density are related to each other. The more dense the air, the more heavy it is, the more pressure it has. But also they are also there's also a small nuance, so they are also different. Okay. So since we know that we can talk about the layers of the atmosphere, the first and foremost layer that we also as humans live inside is a troposphere. And then Iran like they're, they're changing why you may ask because the shape of the Earth is not a perfect sphere, we know it's like called geo it that means in the in the in the poles it's a bit you know, like it like a squeeze in the polls.

Like there's not another perfect, perfect shape but like this I'm drawing an exaggerating form, but like this, okay so in a quarter it's like, is a bit like a has a belly there, but in the polls it's really stretched or like really squeezed, which means when you're in the polls you're closer to the core, the source of gravity but in a quarter, you are far away from the core, which means the gravitational force, even the small amounts even in in in really small amount, but it's Through, its different inventing quarters gravitational forces lower than in the polls. Maybe as As humans, we don't feel this difference too much. But air molecules certainly do. So the shape of the atmosphere is also similar to the shape of the earth, the shape of the atmosphere is more or less, also in a joint shape. This is really important.

So that means the length or like the height, or the thickness, so to say to thickness of the layers of atmospheres change, and it's not certains change always. So these numbers is here, for example, the troposphere, this has a thickness of 12 kilometers, but it's also like an approximation, just to keep in mind because of the reason that I talked about. So what's there on 12 kilometers then the other the second layer From the bottom calls stratosphere, which is around 12 kilometers to 50 kilometers, okay? These two layers is really important for us as aviators because the all the A airliners are flying upper upper border, upper limit of the troposphere, and there is an imaginary excuse me there's an imaginary border between troposphere and stratosphere, like we can draw it, which we call this triple pose. Triple pose is the upper upper limit of troposphere, which divides it between stratosphere troposphere, this is called triple pose.

You can say this is the general rule. This is the general suffix we can say. So, for the other border that divides between stratosphere and mesosphere, we can say startup pose, and this goes like this. Okay? After startup pose. stratosphere and the start of pose we have mesosphere.

Mesosphere is another layer which also contains the which we call ionosphere is fear is like a another layer in between, which call which includes ions as the name suggests, this ions in the check chemistry means, like loaded particles that are electrically loaded like negatively or positively but most negatively loaded particles, which is really important and vital for us because the radio waves for longer distances can only be carried through this ionosphere, because normally in air they need to have ions or loaded particles to you know, like, let's say like carried over bounce over this particles. But normally in the air if there is dry and contains no eye ends, there is no way for them to be carried over, they can, but it's really the ionosphere makes them really easy to reflect okay. So for example in like I can extend this atmosphere here. So, one part here, they can reflect this as radio waves here and can be carried away and the other side of the earth okay?

So this is really vital. So mesosphere contains this and then this coal term sphere. As the name suggests, thermo means a temperature is really hot, because also it's really close to the sun. And then come comes exosphere. Most of the satellites are you know, having this their orbit there. And there's an arbitrary upper limit which is defined is 10,000 kilometers.

But this is not normally the case. The upper limit of the atmosphere can be defined as the when there a prospect pressure is equals to zero or constant Then it means you are outside of the atmosphere. So, I know this is strange rule but it is there also for thermosphere, when the when you see the aura lights in the poles sometimes they are happening at that that layer and in the metal sphere you can see from the from the picture the metal showers astroid showers, they are happening like this when when they are inside this layer disclose, they are becoming burning and you can see them okay. In the stratosphere some of these supersonic military aircraft can fly in the you know, lower lower parts of the stratosphere and most of the meteorological and measurement balloons and they are going as high as stratosphere and then goes down.

Okay. So this could be a summary of the layers of the atmosphere So, if we can go a little bit to detail and recap, most of the commercial airplanes fly at the triple pose, which was the line that divides between that this constitutes the border between stratosphere and troposphere. So, triple pose in order to save fuel since the density of the air is very low at altitude, why we know because when you go up and up in the atmosphere the air density goes down air becomes less dense okay. When there becomes less dense drag force exerted on the aircraft is becoming lower because it's hits. So to say the knowledge it hits less and less air molecules okay. So that is to say few military supersonic aircraft, which means supersonic faster than sound aircraft can fly at low levels of stratosphere there are certain other layers that as I mentioned atmosphere, the significance of these layers are then being enabling the transmission of radio waves, television radio communication system waves are sent to the ionosphere, then reflect to the receivers okay.

Okay, this brings us to another important notion of notion of visibility, we can define the notion of visibility as the farthest point that you can see an object as an outline, or we can call like this we can put like this, the distance between you and the farthest object that you can see a as it's as an outline, okay? You don't have to see it like in real really detail, but it's the distance between the object and yourself. The farthest object that you can see And yourself this is the visibility. So it's like a length is measured as length. For example, if I say the visibility is three kilometers today, which means I can see maximum three kilometers away, but no further away okay. So this is really important for so why is it important because for aircraft to fly, they have to they have to do pilots the pilot has to or the air planes have to see what where they're going and the other traffic's other aircrafts in order to be separated them in order to be, you know, in order to safely carry out their operation.

So this in this picture, you're seeing a runway, but we cannot see the end of the runway. So this is an example. So you're you can start the role of your takeoff you can give to trust your engines and start to roll off the take of gaining speed speed. Then accelerating, but since you're going really fast, but also it's really dangerous that you don't know what's inside this fog or what could be at the at the end of the runway. So you can imagine that when you are really at a high speed, a car or a person or any other team that can cross your way, this is really really dangerous. So you need to see where you're going.

So, since there are a lot of instrument navigational aids that the airlines using today, but they also need to have some certain of visibility to to operate. So all fd aircrafts has their own charts, the aeronautical map, so to say. So, these charts includes minimus we call say minima, these are minimum amounts of visibility and other you know, other notions that Add that that is required to have a certain operation for example, and for this as a occur a airport and also disrupt a specific runway in the chart, you can see if the lights working on you need to have at least minimum 300 meters visibility for takeoff. So when when they measure it by the metrology stations and let's say this visibility is not 300 meters but lower let's say 200 meters then this aircraft cannot operate. That means that it cannot take off. And as a passenger, the end result is that your flight is either delayed really long, I mean until the focus, you know dispersed or the flight being canceled.

So this is really important. So the next time is a passenger you or many many Your relatives or your friends do not understand why my, you know, my my why why my flight is delayed or why my flight is not happening is canceled because of the fork. So of other weather events like storm and other weird or you know, snow or high speed wind, you can say that forgiveness seems to be dangerous, why they can't take off why they can't land. This is the reason because there are certain minimums to be operated and they they really, they're really not empty. These rules are really important. As you can see from from, from my little example of this bromby Okay, so, this brings us to Clarke types, which is really interesting.

So, we can see this picture really summarize it all. But first I need to draw some lines. So the first line is like this. And the second line is like this oops sorry draw like again okay then the second line is like this okay. So, this line, the first is low altitudes and this part is made out to okay. And this part is high out today.

The first thing this so when you look at this picture and the name seems really flattened, lame seems really could be seem complex or frightening, but don't be. Now I'm teaching you the basics the tricks to remember to recognize and also to memorize them. So first you need to know low mid and high altitude there are low altitude clouds, mid altitude and high altitude high clouds okay. The other take, there are certain prefixes or suffixes Okay, the first prefix is C u m or cumulus cumulus means like in packs or in in in in dance and or like gathered down okay? And there's another suffix or prefix This is Stratus or strata strata in Latin means like a surface like layer okay. So, this is like a you know spread over like a layer of like a table or like a plane okay.

And accumulates is the opposite cumulus is not like a plane, but like a small small masses, small gathered masses Okay, packed together okay. So these two important prefixes, but also we have alto prefix alto means many In lead, okay. So, when we look at the low altitude clause we have cumulus which looks like this, which is the I call them you know, cartoon cartoonish clouds. This is like the very basic class this like small packs of cotton, okay, you can see them and we have strutters structures remember what it means like a play like a you know, like a little scattered across like a disk kind of free plane like this. Okay. This is practice.

But when you combine them cumulus and Stratus, it becomes strata cumulus and start with cumulus is mix of them. It's all like both like a strata, but also like packed so they are easy. The low altitude but when we go up to mid altitudes, and we have strutters and cumulus again, but in the beginning, we have the alto prefix means MIT. So this signals that this is a Stratus cloud, but not in the low altitude, but in the mid altitude. And this goes for the ultra cumulus Also, these are cumulus clouds but not in the low altitude in the mid altitude. Okay.

So now we have another type of cloud which is different. This is serious, okay. cirrus clouds is like a small feather, or like threats we can say. And cotton track we can say, like, hang these threats. Like a these contents really crystallized ice and water vapor inside, but since they're really high, and when you go high, the temperature decreases in the atmosphere. At least this is true for at troposphere and stratosphere.

Maybe it's not true for other layers of atmosphere, but you can remember this troposphere in troposphere and such as Fear when you go high, the temperature goes down. Okay? So let's remember again, when you go high, air temperature goes down, air pressure goes down, and air density goes down. Okay, so this is another rule, okay. So since it's really cold, these molecules become crystallized and you know hang in the air like this, when the cirrus clouds becoming like a, you know a plane, I mean like a like a strata, Cirrus Stratus. And when they are becoming packed like cumulus then becomes Cyril cumulus, okay.

So these are all the cloud types, but you can see here folk folk, and we will talk about that later in a minute. But the folk is basically a struct is cloud, but you know, formed and created It happened really close to the surface of the earth. So this is basically cloud but happened really, really close to Earth. Okay, now we have two other clouds that have precipitation raining down there. I will talk about them in a minute but let's see about this contrails maybe some of you have a hunch. What could they be?

But this explain this contrails are the trails of the aircraft engine, basically jet engines. You can see jet engines doesn't it doesn't leave a trail behind after the after them and when they are in low altitude but when they're getting higher and higher, so as a general rule of thumb after they are, they are if they're higher 26,000 feet or above. They are their exhaust gas which is hot. They are becoming visible, why you may ask because they when about 220 to 6000 feet, the air temperature decreases in the extent that this this hot exhaust gas becoming visible. We can talk about we can we can understand this, this phenomenon by an example. When when it's cold outside and when you speak to each other, you can see visibly your you know breath hot breath hot air coming out of your mouth becoming visible.

This is exactly like that, then they're becoming visible. And since the air pressure is also low in higher altitudes, they are becoming you know, like drink frozen, like, not frozen but hang in the air and not dispersing so you can see them a way of discriminating contrails from cirrus clouds is contrails are most of the time almost always linear, but cirrus clouds are chaotic and they are not so linear as you can see. Okay, so this brings us the elephant in the room, the cumulonimbus and Nima Stratus. Clouds. You can see these clouds are not so you know in in planes. They are not so in layers, but we call we call them vertically developed clouds so they are vertical, they're like towers.

And for number Stratus it can be in both in low and mid altitude. And for cumulonimbus, it can be in all altitudes it can be really high tower. So these are stormy clouds and really dangerous class because inside them they carry really, really, really high and really, really dangerous icing and high speed, wind and Storm and they are also you can see they're really humid because they are, you know, leaving dropping they're all water as a precipitation, like, like rain or snow. Okay, so these these clouds are these are not all the class that can happen in our sphere. But these are most common ones and we need to know them. So for cumulonimbus and nimble Stratus, as a pilot, you need to recognize them first and then avoid them.

Okay, so let's talk about some of the weather events and how they are forming how they are happening and also how they are affecting our aviation operation. Okay, so rain, so humidity, or is the amount of water vapor there so we call water vapor and in the air in the atmosphere as humidity. Okay. So, we can calculate the relative humidity, which is calculated by dividing absolute humidity by maximum humidity and multiplying it by 100. And the end result the relative humidity is a percentage, okay. So that's why we are multiplying it with hundred this ratio.

So this ratio, now I need to explain you the what is our absolute humidity and what is maximum Mitie. The maximum humidity is the amount of a air mass, the maximum amount the maximum amount of water vapor that an air mass can contain. After the maximum humidity, the air mass cannot carry more water vapor inside it. But for the for the the other other term here absolute humidity is the amount of humidity that carries currently So the relative humidity you can say the percentage of for an air mass the the percentage of how its tank full you know the how much is its its humidity tanks is full or not. Okay? So let's give it an example.

Let's say we have an air mass here and this air mass the it can carry let's say one tone of, you know one tone of of water vapor okay one tone of watermelon water. So, and also absolute humidity could be like, what we can say, like one tone is which means 100 knots 100 1000 kilogram right? Okay? So thousand kilograms, but for absolute humidity, they let's say it is 700 kilogram, okay, so it's Now carry 700 kilogram of water water molecule water and matter and the maximum of it is 1000 kilogram. So, when we divide it The end result could be 70% right 70% So, when this relative humidity reaches 100 which is hundred percent, then after that point this water cannot be carried because it's like saturated with this water and it cannot carry it and this becoming full falling down to the earth okay.

So, how this rain occurs. So, actually the old precipitations are curing because of the dis this How can I say this rationale this mechanism okay. So, but for the absolute humidity or maximum validity, the absolute emitted is not changing when an air mass travels You know, in in in about a, you know, let's say of see the water, you know, becoming vaporized and goes up, up up and then the air mode, the the clouds are loaded with it, you know, and there's absolute humidity that there you're carrying a water, but maximum validity can be affected by many factors, one is the temperature and the other is the air pressure. So, you can see by now, this maximum hood, then it's also affected by the altitude, because we know that when you go high, and the air pressure and air temperature is also changing. So when the temperature goes down, when the air getting colder and colder, it can it the maximum and level but maximum humidity it can carry goes down, also, when the pressure goes down when the pressure is less pressure and also To the maximum if it goes down.

So, that means for example, this water mass goes like travels like here to a coastal region at sea here and this coastal region has mountain here okay. So, when it comes here, this mountain forces is to you know, go high, but when it goes high, what happens the temperature goes down and the maximum humidity goes down. So, nothing happened to absolute humidity it still carries 700 kilograms, but since the maximum event it goes down to for example, 500 Okay. Then all of a sudden this relative humidity goes over 100 and it cannot carry this water vapor any longer and this water vapor becomes How can I say from the gas becomes from from from the gas to the flute, state of the matter, and then it goes down like rain. Okay, so this is the basic principle of how the rain or cures that brings us to snow and hail.

Snow is like when this waterway per a just skips or bypasses the part of becoming a flute, but just going to true the 3d state of being a solid, okay. So instead of from the guests phase, it's becoming fluid and solid, but the DD is for the snow crystals to happen. They are becoming in really, really small microscopic amounts of flute and then this flute froze this but this is really small microscopic it can fly on the air and this small crystals when they're becoming together, they are forming the snow, this the white snow, but when we see on the right side you can see the Hail. Hail is a different kind of thing. What happens for example, like in the in the higher altitudes here, the raining happens and we have you know drops of water, okay? But when they're going down, they can come across really, really high, really, really cold freezing zone.

And they're becoming frozen inside there and dropping to the earth like frozen particles like hail. But for snow, there is no such layer called layer. They are becoming like really, really small molecules of water and crystallizing and dropping down as a general rule of thumb In order for snow to happen in a humid weather like a like rain weather to become a you know snow, the surface temperature of the earth surface should be four Celsius degrees like positive plus four Celsius degrees all over. Okay, the four and all over, then it becomes snow. So that brings us to fork. Hard fork happens as I mentioned earlier fork is basically a, a Stratus cloud that can form that formed really close to Earth.

And form fog is a visible mass consisting of cloud water droplets or ice crystals really, really small, suspended in the air at or near the earth surface, okay, so four can be considered a type of low lying Stratus cloud and is heavily influenced by nearby bodies of water, topography and wind conditions, because it needs to be really cold. You can see one day if it's really humid and hot, and other day there's a sudden drop of temperate air temperature, sudden coldness, then there's happening of folk the possibility of happening fog is really increases, you can see the fog so you can do your own forecast here. So that brings us another important notion for, for for aviators. This is the how the possibility or probability of fork happening and calculate because fork is really really important for us because the the the the cardinal reason to visibility to to decrease is the fork.

So many of things can decrease the visibility which is really important for us for the affer mentioned before mentioned reasons, but for visibility, for example, rain can decrease the visibility day and night cycle for example, in in the night visibility decreases dramatically, but also fog is the first and foremost reason or dddd The reason that decreases visibility. So, fog is really important for us and we need to you know have a certain calculation of the probability of folk happening or visibility to decrease to plan our you no flights. So, we have two things we have div point and air temperature, dew point is the temperature. The pre calculated temperature is the point where the in the air boil kill molecules becoming like doo doo you becoming the curing do starts Akira okay and the viewpoint. So, air temperature is the air temperature. So, let me explain with an example we have for example, the D pre calculated dewpoint which you can have from the metrological report, the dew point is like say 15 degrees Celsius, okay.

And the air temperature is 16. That means air temperatures really close dew point and what happens if there's a danger in the dew point around 15 degrees Celsius, the humidity the water vapor inside this test has sustained indoor air mass becoming visible and becoming like sublimated and becoming like a deuce inside like fog. Okay, the particles becoming visible. So, as we all know, they're they're always water vapor in the air, but we don't see it, but when it's in a certain tempo It becoming visible and by becoming visible it's also obscures our our visibility our sight, so decreases the visibility okay. So, this is like this. So, since if these two two temperature dew point and air temperature becomes closer or identical and the more they are becoming closer the more the probability of become like fog or visibility decreases is increased its probability increases okay.

So, there is another thing really populating turbulence you may have experienced this during your you know airline air travels and journeys, but turbulence is no more than a you know the disruption of of the air mass Okay, smooth air mess. So, when stuffs smooth this is turbulence in fluid dynamics and Air is also fluid here, turbulence or turbulent flow is a flow regime characterized by chaotic changes in the pressure and flow velocity. Okay, so that means turbulence is like a air that's not so smooth, you can think of like a water with a lot of waves in it. turbulence is caused by the relative movement of disturbed air through which region aircraft is flying. Its origin may be terminal or mechanical. And it may occur either within or clear of cloud.

But inside the cloud, the probability of turbos happening is increased, so it's more more possible. The absolute severity of turbulence depends directly upon the rate at which the speed or direction of airflow or both is changing. So, although the perception of the severity of turbulence which has been encountered will be affected by the model Have the aircraft involved. So, that means for example, we have an air mass here it is really you know, we can say like really smooth just like this. And when you when an aircraft goes inside it smooth, but another air mass, it can be like this, this is really happening inside this troubling like boiling maybe it is because there's a hot spot here and this heats the air and the heat and air has a tendency to go up like a con con directional movement we call this like this. This is like this goes up, goes up goes up okay.

Then there's a turbulent movement and when an aircraft goes like goes through it, it It feels this turbulent okay. This is the this is the terminal reason, but for mechanical reason. For example, this aircraft goes through the smooth air mass and Makes it you know really juggling and cultic this this is you can think of like a we have a like smooth surface like smooth surface of water. And then when a when a really high speed, speed racing boat goes through it and after it you can see it's after wave, okay, it disrupts the water smoothness, this is like this turbulence like this and on the contrary to popular belief, it is not the most. It is not the first reason for a accidents, it's not so dangerous even. And this is the last weather event that we are going to talk about is the wind.

So how does wind occur here? In the previous lecture, we talked about Mother Nature's wind and the relative wind. relative wind is a relative feature Or a thing because of because happen happens because of our movement, but the mother nature's wind, I didn't explain that now we can explain it as I said before, the nature's law is says like this goes like this The when a mass is denser in in one location and less denser another location, it has a tendency to equalize this disequilibrium. So, mass is usually especially the flutes usually moves tends to move from when they are most dense to less dense, okay. So this this is the direction of the movement. So, you can see this isobaric isobars, this is like isobar means equal pressure.

So these lines means represent the pressure levels here. So, this is a 1016 million bars are hecto Pascal's. So by the way, they did standard air pressure standard. And when it when you ask when you're asked the standard air temperature air pressure, it is like 1013. So 1013 millibars Okay, or it's equal hecto Pascal's like this. Ah, PA, okay.

Hecto Pascal's very cool, but also for an American side, you remember the FAA, they have their own terminology. So they are using a different measure of the same thing. They're they're measuring the same air pressure, but they're using the inch and inch Mercury, okay, inch mercury thing. So this also equals to 20 nine point or 92 inch inch Mercury, okay? They are using this they're all equal. So this is this is 10 1016 millibars and 992 millibars.

So that means the air pressure is high here at low here and you can see H and low to represent it. So what what that means if it's hot it's a the pressure is higher here means the air is denser here and less than here. So which means as a general rule of thumb, when it is dense, it travels with where it is dense to less than so it would like goes like this. Okay, so wind is a relocation of air molecules when they are dense to when they were where they are less dense. Okay, so The speed and the no strength of the wind depends on the pressure difference, the more the difference between the pressure zones, the stronger the wind, and more close the closer they are, the closer they are to pressure zones pressure cores, they are closer and then they win the stronger and faster.

So I Lastly, I put this a funny image here. Because when I was a kid, I was, you know, imagining like there was someone that puffing in the sky or the God was puffing in the sky that create that that was the thing that created the wind, but now we know it's not okay. So, this completes our a lecture on introduction to aviation mythology. See you in the next lecture, which We'll be about introduction to aviation Fraser logy