See, this is the first chapter in navigation. Navigation has three parts, general nav, radio nav, instrument nav. Navigation DGCA CPL exam has 100 questions in which general nav will give you around 35 questions. Exam is not important. Understanding everything is important.
because as a pilot most of the times in your cpl during your cpl you you will be flying the aircraft alone correct so 100 hours is the requirement so you should be able to navigate aviate and communicate the minimum correct to be safe and of course the safety of passengers depends on your knowledge levels correct and also getting a license here there are 3000 people or more than 3000 people with a license sitting at home doing nothing because here only the cream will get the jobs correct so the more you understand the topics it will be very easy for you to crack the airline entrance so this being the first chapter it consists of a lot of basics correct So once you are very clear with the basics, when you move on to the next convergence, when you move on to radio navigation, it will be super easy. Okay. So first three days are very important.
Okay. So what do you think the shape of the earth is? What is the? It's G-O-L.
What? G-O-L. Okay.
I'll give you options. What is the? shape of earth options are a circle b spear c ellipse d ellipsoid e oval f oblate that means oval when you mix with spear oblate spheroid g geoid choose the correct answer you told you so tell me what is a circle what is a circle circle is basically an arc uh infinite arcs which have same radius okay from the engineering background that is correct from my point of view this is a circle which is a two-dimensional round structure correct so if f was a circle correct you would walk you walk somewhere you will fall into space correct so earth is not a circle correct so circle is not the correct answer now is the earth sphere correct do you see the globe the globe is round correct so is the earth round like this is the option sphere correct see to be able to call this as a sphere it should have equal radius on all sides correct its diameter should be equal on all sides but see do you see the earth it is compressed like this okay so the polar diameter is less than equatorial diameter understood so sphere is not the correct answer correct same way same like sp if this is the circle circle is a two dimensional if the same thing which is a three dimensional it is a sphere correct Now see oval or ellipse means the same. This is oval in which there will be a major axis and a minor axis. Correct.
This is a two-dimensional structure. This is called as oval. Earth is not two-dimensional.
So, oval is not the answer. Even ellipse is also the same. Ellipse will have a major axis and two minor axes like this. Correct. So, this is a 2D ellipse.
This is not the correct answer. See, earth is a ball like this, correct? Three-dimensional structure which is compressed in the polar axis.
That means, earth is like this, correct? It's a three-dimensional structure. Now, this axis joins north pole and south pole, correct? so this axis is called as polar axis this axis is called as equatorial axis because see this is the equator right so this is the equator this axis is called as equatorial axis from now on i call equatorial axis as ed polar axis as pd let me clear next now if you mix this 2d oval shape with a 3d sphere what happens you will get a shape like this oval plus sphere do you see the cross section will be oval for this but it's a three-dimensional sphere so oval plus spheroid sphere called as oblate spheroid is the correct answer that is also correct answer correct same way if you mix ellipse plus sphere it is called as ellipsoid that is also correct answer am i clear now see what is meant by cardiology cardio means heart logic means study of study of heart correct what is meant by card cardioid see when i teach you radio navigation i'll be teaching you something called as polar diagram of ndb non-directional beacon there i will mention something called as cardioid because that diagram it looks like heart correct oid means looks like or similar to similar to cardio means heart same way any shape correct if you take a ball or something or anything whose shape is similar to earth see earth in greek is called as geo correct so similar to earth any shape is called as geoid so this question has three correct answers in which you answered one correctly am i clear on this hushwagar correct next here Let me ask you a question because I have taught you something.
Now it's my turn to ask a question. Again, what is the shape of Earth? Options are oblate spheroid, ellipsoid.
it's a flat circle choose the correct answer so it's a and b you have to choose only one see when you see this question in exam go for oblate spirit because this is the bookish definition of the shape of it correct so when you don't find oblate spheroid go for ellipsoid when you don't find ellipsoid go for geoid am i clear on this am i clear on this yeah tell me if this is earth correct it has two diameters correct equatorial diameter and polar diameter this is pd this is ed correct now equatorial diameter is greater than polar diameter do you agree that's why it is oblate spheroid correct so question is by how much the answer to this is 23 nautical miles clear so ed is more than polar diameter by 23 nautical miles now so i'll tell you a small story which happened to me during my navigation exam see let's take this is the exam hall correct let's take this is the exam hall so i gave my exam in delhi this is the exam hall correct now there are computers like this see i was sitting here and there was this guy sitting here correct and people were writing exam like this Now, invigilators were roaming like this, up and down. The guy beside me called the invigilator and said, Sorry, this is me, correct? This is Vamshi.
This is the guy beside me, Mr. X. I don't know his name. So, he called the invigilator and said, Sir, I am hungry. Exam is going on.
I was like, what are you doing here? Let me write my exam. You're hungry. So what's Invisalator said?
Invisalator was a nice guy. Here, I will get you tea and some biscuits. No, no, sir.
I want Domino's pizza. Invisalator also got angry. Correct. I also got angry.
Here let us write the exam. Sir, at least give me the toll free number of Domino's Pizza. I will call them after the exam. He was making argument.
And finally, Invisalator gave the number. You know, what is the number? 6888 6888 Do you see?
Domino's pizza's toll-free number, correct? Toll-free and customer care number. Now see, you know, then I realized why this Mr. X has asked for Domino's pizza number.
Because in exam, the question was, what is the equatorial diameter of earth? Correct? The answer to this is 6.8. nautical miles but this guy na mr x did not remember the value so he asked the invisulator when the invisulator gave the phone number 688688 he remembered the equatorial diameter is 688 nautical miles am i clear correct next here now equatorial diameter is more than polar diameter by 23 nautical miles you can i write ad minus pd is equals to 23 nautical miles can i write this now what is the equitable diameter six triple eight nautical miles minus polar diameter is equals to 23 nautical miles so polar diameter is equals to six triple eight minus 23 that would be equal to six eight six five nautical miles and the difference between ed and pd is how much 23 nautical miles so polar diameter will be how much so ed minus 65 so these are the questions correct now i'll ask you a question tell me the answer okay let me take a line and i name it line a let me take a line and I name it line B correct which of the following is bigger line A or line B line B line B is bigger correct now this is line C now which of the following is bigger line C correct see initially when I draw a like this line B was bigger but now when there is a bigger line line B became a small line correct same way see there is something called as compression of earth now question to you earth is compressed like this by how many nautical miles 23 its compression ratio is 0.3 percent no no no i mean i i am trying to uh ask you that if it is compressed like this it is by how many nautical miles 23 23 nautical miles correct so earth is compressed by 23 not comes i know you have read the notes correct and yeah fine see this 23 monocle miles is equatorial diameter minus polar diameter this is compressed but with respect to what see it is compressed with respect to the highest diameter correct when divided by six triple eight nautical miles or when divided by equatorial diameter this value ed minus pd by ed is called as compression of earth am i clear so compression of earth means equatorial diameter minus polar diameter when compared to equatorial diameter am i clear on this Now this will give you how much? Approximately 1 is to 300. Some books will mention 1 by 297. Take it as correct answer.
So what is the compression of earth? 1 is to 300. Am I clear? Yes, sir.
okay question compression of earth expressed as percentage options are a 0.03 option b 0.3 option c 3 answer please 0.03 percent you have given this answer correct i'll tell you td minus pd by ed is the compression of earth that is 23 by 6 8 this will give you 1 is to 300 correct now when you want to express this value as percentage you will multiply this by 100 correct so this is multiplied by 100 so it will give you 1 by 3. that is 0.3 percent correct why i ask this question is many people i have old students who in spite of telling repeatedly in exam they will go and write 0.03 percent correct so what i want you to do i want you to strike this off like this write the same question you know strike this off like this and put a tick mark at 0.3 am i clear on this this is the first slide shape of earth oblate spheroid ellipsoid or in greek language geoid correct now if you take the polar diameter that is six eight six how did you get it because pizza number was like domino's visa number six two eight six two eight correct so six two plate is the equatorial diameter equatorial diameter is more more than polar diameter by 23 nautical miles correct if you substitute it you will get polar diameter am i clear so compression right you are com comparing this 23 nautical miles that show to because to cho to to someone who is higher than them correct so we have to compare the difference 23 nautical miles with equal diameter 6 to blade correct then only will come out correct that will be equals to 1 by approximately 300 or approximately 1 by 297 correct see all the units will be nautical miles in today class or tomorrow's class i'll teach you what is a nautical match correct next compression of it this is okay compression of earth expressed as percentage 0.3 percent right 0.03 percentage and strike it off clear first slide is clear shall i move on now how many of you are very good with algebra none of you simple question if you take two accesses correct let's take this is y axis this is x axis correct now what is this place called as what are these called called as coordinates quadrants quadrants quadrants first second third correct so this is the upper right quadrant correct upper right quadrant this is lower right lower right quadrant lower left quadrant so these are called as quadrants similarly if you take earth so i'll draw earth on super i'll superimpose earth on this right see this is north pole this is south pole now This direction is east. This direction is west. Correct.
Now, the other parts. Correct. These are, this is northeast, southeast, southwest and northwest.
Here, all this northwest, northeast, southeast and southwest. These are called as. quadrantal directions. North, east, north, west, south, east, south, west. Am I clear?
Here put a star mark and five below it. Till now I have not seen a single exam paper without this question. Which of the following is a quadrantal direction?
They will give options like north, east, north and west. correct it is easy in if you take xx and y-axis it is called as quadrants same way these in this also northeast northwest these are called as quadrantal directions correct now how many of you go to church i also used to go to church one of my best friend regularly goes i generally now and then goes with him here see you know they talk about cardinals correct so cardinals are very important people either for example if you take vatican city and all they live there correct in a very big church the heads of the church are called as cardinals so by definition cardinal means a very important person or thing a very important person a very important person or thing correct so here east west north and south these are called as cardinal points East, West, North and South. Am I clear? Cardinal points or directions?
Cardinal points. Am I clear? See because this is described terminology and is considered standard.
So we have to understand that English. like that only am i clear now here one funny question i'll ask if you take this as earth this is the north pole this is the south pole here if you are standing like this at north pole And if you are looking like this, towards this, correct? Now, which direction are you facing? If you are standing exactly at North Pole, which direction are you facing?
East. I'll tell you. See, I mean, it is a very funny question, but I like this kind of questions.
I also gave the answer East when I first listened, had this question. See. Now, this is the North Pole, correct?
This is the South Pole. Okay. Let me take the flow.
North Pole, South Pole, correct? Now, if you are standing here like this, correct? See, if you go any direction, you will reach which pole?
South Pole. pole correct you will reach south pole you will reach south pole correct so the thing is see you have to go you see i mean you travel any direction ultimately you will reach south pole correct so there is a question here if you face any direction from north pole correct which direction are you facing see at least it is very rare that you will you This will be exactly 90 degrees. Understood. So, any direction if you face or you go on the earth, sorry, or like this, you will reach South Pole.
So, if you stand at one pole, you will actually face the other pole. Or if you try to move, you are moving towards the South Pole. How many of you understood this? Correct. i mean this is a very beautiful question i kind of like this question even i thought here somewhere east and west will be here now i'll be facing here no no no see if you this is not see if you have to go to east and you cannot go from a pole here maybe on an earth you can stand here and if you go along this line you will go north pole this is north this is south and along this latitude if you go east this is east first but at the pole you can go only to other pole opposite pole understood am i clear yes next funny question but i believe it's good question sun rises in the east and sets in the West Option A, true Option B, false Who, sir?
Mantan Here, is this a tough question here? True, sir. True, sir.
Varun, Azhar, Ankar, Darwin. True, sir. False, sir. True, sir.
True, sir. Everybody said true. Anybody wants to say false?
Varun wants to say false. Here, Varun, what is your explanation? The earth goes around the sun, not the other way.
So, sun does not rise. It appears as but it is rising. Correct.
So, you can say ki, yes, sun appears to rise, not sun rises, sun appears to rise in the east and sets in the west. this is a very correct statement but not the sun rises in the east and sets in the west for example let's say my yellow ball is a burning sun and this is there okay now see let me fix or i'll take mic as the sun it will be easy to hold correct now see this is india correct you are standing at india correct you now when you are opposite to the sun when you are facing here i i'll show with this my pencil when you are facing here that means you are experiencing midnight because the sun is not falling on your side correct then slowly the earth moves like this the earth moves like this earth moves like this earth moves like this now at now it is like five o'clock in the morning correct now it the sun rays will start falling on you six o'clock in the morning correct and again afternoon so earth is rotating around itself correct that is why you see as if the sun is moving from east to west sorry correct so sun you sun will appear as if it is moving from east to west but actually earth is rotating from which direction to which direction integral west to east west to east very good correct so earth rotates from See, I did not give the answer. Correct? You only gave the answer.
So, earth rotates from. The answer would be west to east. Am I clear?
Am I clear? Next. Here, Mantan, whatever you said, the answer.
it is only half correct correct you said anti-clockwise and west to east i'll show you how okay let me put it as a question in which direction the earth rotates is it a clockwise is it b and a clockwise now what is clockwise if you take clock 12 3 6 9 so the needles will go like this correct this is clockwise correct if you go 12 3 6 9 in the opposite sense this is anti-clockwise answers please manthan you said anticlockwise yes sir others both who said both sir how can i rotate like this and like this so if we look at from the top then very good very good very good the answers are both correct now see at this going from west to east south clockwise now if i look from the top it is anti-clockwise correct now if i look from the bottom it is clockwise correct if i look from the bottom it is clockwise if i look from the top it is anti-clockwise correct now write down rotation of earth as viewed from north pole is anti-clockwise from south pole is clockwise am i clear this is also a question and you should see this kind of thing should become imprinted in your brain understood i mean i i want you to imagine really at going anti-clockwise like this this is the sun it's just going like this right next tell me how many of you are very good with english you are becoming pilots correct so everybody should be good with english okay here my teacher you should stay tell me in school if there are two words in english with the two different spellings they always have a different meaning Am I clear? What is the difference between rotation And what is the difference between revolution? Rotation is that rotation from the axis. On one's own axis.
What is meant by revolution? Revolution is revolving around the sun. See, let us imagine this mic is the sun and I am the earth. Correct? Now, I am rotating around myself like this, around this axis, around the axis in which this chair is placed.
This is rotation. Now, if I stand up and if I go around the mic like this, while rotating, I am rotating and also going around the mic like this. So, this rotation is different and this part where I am going around the mic, that is called as revolution.
So, if this is the sun and this is the earth. so earth is rotating around its own axis but at the same time it is also revolving around the sun correct write down rotation means moving around its own axis revolution means going around the sun correct now is the earth rotating or is the earth doing revolutions both both at a time correct your rotations will give you day and night the revolution will give you seasons okay let me show you how okay okay tell me here see i want you to search after this class on any shopping website online and to find a globe which is perfect here look at me look at this i spend around thousand rupees for this and it is theta i mean it is here it is is it's right is my thousand rupees waste no it is not waste explain here explain why Sir, it is inclined to magnetic. Is it because of the magnetic knot? Magnetic which is not. No, no, no, no, no, no, no.
I will explain. I will explain. Let us see.
Let us take this as the sun. Correct. Let us take this as the earth. Correct. Now see, the earth is. going around the sun like this correct so from here the earth will go here here here here this is called as what revolution revolution correctly now if you join a line between the center of earth and center of sun correct earth should rotate around itself also correct now See, let this be the center of earth.
You may be thinking, sir, earth will be going from which direction to which direction? East to west or west to east? West to east. West to east, like this, along this perpendicular axis.
This is called as normal axis. correct this plane this plane if you join sun and earth center this is called as orbital plane or ecliptic plane correct that plane so that means like if you join this is the sun and this is the earth if you join the center of earth and center of sun center of earth and center of sun that plane around it in which the earth rotates this plane is called as orbital plane understood now see the earth is not like this earth is not like this earth is not rotating so rotating around itself like this it is rotating around itself like this so it is inclined with this axis correct now the actual axis of the earth is this axis correct so the earth is rotating around itself in this axis this axis is called as polar axis correct so this is north pole this is south pole that is how they decided south pole and north pole correct and if you take this ball correct it is rotating around itself like this this point is decided to be north pole and this this is south pole correct the extremes extreme points of axis of rotation of earth or polar axis is north pole and south pole correct now See, the earth, it is not rotating like this. It is rotating from west to east like this.
Am I clear? So, what is this? This is called as polar axis.
How many of you understood? Raise your hands. Correct. do you see this inclination correct from the normal axis normal axis means axis which is perpendicular to the orbital plane or ecliptic plane correct from here the value of inclination is 23 and half degrees or 23 degrees 5 30 minutes or 23 and 23.5 degrees correct So it is 23.5 degrees. How many of you understood?
See here if you understand, I will ask you a question and you should answer it correctly. Question. What is the inclination of earth? Options are. 23 degrees option b 24 degrees option c 66 degrees options d 66.5 degrees choose the correct answer one second here i'll just come back by the time you decide your answer Get the answer please here.
Sir, to which... I just asked you a question. There is only one correct answer.
Sir, D. Huh? D. Sir. No, Alpha 23. Alpha Darwin 23. Sir, D.
d oh the correct answer is d see i told you from the normal axis it is inclined by 23 and half degrees correct that means see if you don't have 23.5 don't go for 23 you think here they may be asking from this polar axis also not the polar axis from the orbital plane also correct So that is, see total is 19. Because that is called normal axis, normal means perpendicular. So this will be 66 and a half degrees. So if they ask what is the inclination of earth, the correct question would be from orbital plane or ecliptic plane, it is 66 and a half. Understood? How they can twist the equations.
correct you may think here see you have come to class you have read everything you have remember 23 and half also at 23 is the closest answer now i'll go for it no no no no don't do that go for 66 and half because it is like from the normal axis it is 23 and half from the orbital plane it is 66 and half clear Coming back to our slides, is this understood? Cardinal points and quadrangle directions north, east, west, south. These are called as cardinal points.
Northeast, southeast, southwest and northwest. These are called as quadrangle erections. Is this understood? Correct.
Now, is this understood? This is 23.5. Correct.
From the normal, this is the normal axis. Correct. What is this? Obliquity? Obliquity or, I mean, inclination, both are same.
Correct. Next. here do you see the earth is rotating but it is inclined and i should know here rotation of earth is it from east to east or west to east west to east west to east correct when viewed from north pole how is the rotation anti-clockwise anti-clockwise when viewed from south pole it is like south pole or north pole west to east anticlockwise correct you imagine don't remember here see always don't remember things because after two or three days after 10 days 15 days you will forget things but once you imagine things you don't forget things believe it or not i have imagined this while i was reading for the first time today i did not come prepared for the class correct i did not read the subject today correct always imagine things they will stay in your mind clear now inclination of earth is clear so this is the plane of earth orbit it's also called as orbital plane also called as ecliptic plane right this is the normal axis now this axis of the earth see earth is not rotating around itself like this this is not correct Earth is rotating around itself like this. Correct.
It is going from west. This is called as west and this is called as east. Correct.
West to east like this. Do you see this arrow? Understood.
Next. Here, take a small break. Correct. I'll see you in 10 minutes.
1, 20, we will start again. Okay. Have a small snack and come back.
I'll have my coffee. Yes. Any doubts? Yes.
So that why, what is the reason it is inclined to that degree? Very good. Let us come back from break. I'll tell you the reason.
Yes. Unkar, your question was, sir, why is it inclined? See, if you ask me.
Correct. Do I believe in God? I think I believe in God. Correct. But mostly when the exams are very close.
But there are some reasons that God must be there. Because see, life on earth exists because of the inclination. Here if there is no inclination there is no life possible on earth because see if you take this as sun this is earth our blue planet correct now see if the axis of rotation of earth is like this correct all the sun's rays will fall directly on the equator correct the sun's rays will be slant on the poles that means at the equator it will be very hot like almost will be like ball of fire and at the poles it will be very cold minus 250 degrees at the equator plus 200 degrees correct now because the earth is inclined what happens is again i will draw a diagram if this is sun and this is our earth now this is the north pole this is the south pole this is the equator correct now earth is a sphere correct almost a sphere right equator divides earth into two parts North and up. North and south.
Correct. Up and down. Correct.
So, upper part is called as northern hemisphere and lower part is called as southern hemisphere. Correct. Now, see the sun's rays are falling directly on which hemisphere?
Northern. Northern hemisphere. Correct. Now, earth is rotating along its axis like this, but it is also revolving around this axis. Correct.
Now, let's see. Let's say the earth is. to this side half of the year is over correct now this is the axis of rotation of earth correct this is the equator now tell me the sun's rays are falling vertically that means half of the year sun's rays will fall vertically in the northern hemisphere correct then it again falls at the equator and then half of the year it will fall in the southern sphere correct That's why, see, India is in which hemisphere? Northern hemisphere, correct? So, India experiences summer here, correct? If you take Australia, which is in southern hemisphere, when India has summer, Australia has winters, correct?
Now, if you go to this position of earth, see, Australia is here, correct? And India is here. Now, India, it is winter.
correct now you google temperature in australia it is very hot australia will be having summer now this is december correct so if we have winter in northern hemisphere the countries in the southern hemisphere will have summer so this is the reason for the distribution of heat evenly half of the earth will receive half of the year northern hemisphere will receive half of the year So nothing will get too hot or too cold. So that is the reason we are able to survive. Understood, Ankur? Who made this?
Probably God. Okay. Probably we are lucky. Correct.
Nobody knows the answer. But this is how it works. This is how we are able to live. Understood? And more to this in meteorology because this is the reason for the...
climate monsoons correct so india lies in the northern hemisphere northern hemisphere correct do you see the globe the silver line is the equator yes so here is the india okay okay in the northern hemisphere in the upper part closer to north pole is the india correct northern hemisphere do you see australia australia is below this is the silver line equator correct this is australia am i clear yes sir your doubt is clear next tell me what is equator we will see what see we i was saying yeah this is the equator this is the equator this is the equator can someone say here one point about the equator one point 90 degrees to the axis of rotation very good Exactly correct. See, if I take this ball, let me take this and draw a line like this. do you see the red line correct this is the equator okay so this axis if i hold the ball here it is the north pole and this is the south pole i mean if you if i put a pen like this if i put a pen like this and put a hole and this like this and the equator will be rotating around this understood so the plane that means what is meant by plane if i cut this ball like this and i look from the top that is the plane of equator understood so if i have to draw it i should draw like this right so this is the axis of rotation of earth correct this is the equator This is the plane of equator.
So the plane of the equator, do you see it is making 90 degrees angle, correct? It is making 90 degrees or like this with the polar axis. How many of you understood what Ongar said?
Everyone raise your hands. Understood. Correct. Next.
Here, see, if I draw a circle like this here, i will also make its plane 90 degrees can i call it a equator no correct now if i draw a circle like this here can i call it a equator when its plane is also 90 degrees no right correct can someone make it better observation greater circle very good see i can draw many circles like this i can draw a circle here circle here circle here correct but see if i have to draw the biggest circle i can draw only one circle which is the biggest at this point correct so above this if i draw a circle it will be small below this if i draw a circle it will be small correct so equator is a great circle equator is a great circle what is a great circle here simple english here we don't want to complicate things the greatest possible circle that can be drawn on the center on the earth correct what is a great circle the greatest possible circle that can be drawn on earth clear so equator is a great circle right now and this is not the complete definition equator is a great so we'll combine the other rule also whose plane is perpendicular to the axis of rotation of earth in brackets polar axis How many of you understood the definition of equator? Am I clear on this? Correct. So equator is a great circle whose plane is perpendicular to the axis of rotation of earth. Okay.
Am I clear? Now what is the great circle? What is a great circle? What is a great circle? greatest possible circle that can be drawn on earth correct so if you draw any at any other place it will be a small circle that means smaller than the great circle is any circle which is smaller than a great circle is smaller correct now let me tell you one more useful fact correct here anything or any value in aviation which is less than one percent is generally ignored anything in aviation here anything in aviation whose value is less than one percentage generally one second i'll stop here and share it back here everybody exit the meeting uh join back in exactly 60 seconds not 60 seconds two minutes i'll just restart the computer something is faulty at my side okay so i was telling anything in aviation which is less than one percent is ignored correct tell me what is the problem value of compression expressed in percentage 0.3 0.3 is it more than 1 or less than 1 percent it is less than 1 percent so generally when it comes to aviation correct for the rest of the cpl subjects correct we will you imagine earth as a perfect sphere correct we can ignore the 0.3 percent compression ratio expressed and we can call earth as a perfect sphere for remaining our navigation correct this is the first time you you will learn the earth is not a perfect sphere and you will forget also at this perfect sphere correct of course nowadays the latest advances have come where they even calculate the elevation of the place, depth of a place, correct?
And WDS, correct? World Geodetic Survey, 84, 1984. They have conducted a survey and they have tried to measure the exact shape of the Earth, correct? GPS uses that WGS 84, World Geodetic Survey 84. But as far as we who are trying to figure out what navigation is, we will consider Earth as a perfect sphere. Understood now is the definition of equator clear equator is a great circle whose plane is perpendicular to the axis of rotation of earth Next tell me tell me how many great circles that means the greatest possible circles can you draw on earth options are a one option b infinity infinity infinity what is that suzel a yet the answer is infinity until you see this is the earth this is the axis around which it is rotating this is the north pole this is the south pole correct now you you have drawn a greatest possible circle like this correct and call it as a equator Because this circle axis is perpendicular to the polar axis.
Now, you can draw a great circle like this also. Even these edges of this globe, this part and this part, this is also a great circle. You can draw like this also.
that means you can draw infinite great circles on earth understood but that great circle whose axis is perpendicular to the poles is equator am i clear on this so you mean to say the plane is perpendicular to that yes yes i mean yes i meant to say the plane of the great circle which is perpendicular to the polar axis correct this is the plane of the equator Yes, that is called as equator. Yes, Varun, ask. This is considering Earth as perfect sphere, right?
Considering Earth as perfect sphere, you can draw infinite great circles on Earth. Correct. For aviation purposes, you will generally consider Earth as a perfect sphere.
Okay. Next. Here, I told you this is North Pole and this is South Pole. Correct. Now, if you take a compass.
Correct. If you are standing here, will it point towards your North Pole? Correct? Understood? You are absolutely wrong.
See, this North Pole is called as Geographic North Pole. Geographic North Pole. Or it is called as True North Pole.
This South Pole is called as Geographic South Pole. Geographic South Pole. Also called as True South Pole. Here, they just thought that Earth is rotating along this axis.
That pole I will name it as North and the pole at the bottom I will name it as South. Okay. But see, Earth is a huge magnet which will attract magnets, which will align magnets. Correct.
earth if it is a huge magnet it should have north pole and south pole correct so it will have a north pole but that will not be at coinciding with the true north pole correct it will have a south pole somewhere here correct because earth is a huge magnet it will act as a magnet but the north pole and south pole of the earth magnet will be at a different place than you the true poles correct so this north pole of earth is called as magnetic north pole correct if you take a compass your compass will show towards magnetic north pole but not towards true north pole correct if you stand here and if you hold a compass it will point towards this north pole but not this correct so magnetic north and south poles are different from geographic north pole and two not poles how many of you understood this concept also clear correct now day after tomorrow's class i'll be teaching you about variation correct deviations and all further this concept is very important understood am i clear this is just i'm just giving the basics of day after tomorrow's class understood shall i move forward with the next concept Equator definition is a great circle. Here what is a great circle? Greatest possible circle.
Plane is 90 degrees to the axis of rotation of the earth. Correct. You see axis of rotation of the earth.
Correct. Equator is this. Correct. It lies in east and west direction.
Correct. East, west. It lies in east-west direction.
Correct. Now it divides the earth into two hemispheres, northern hemisphere and southern hemisphere. Understood?
Understood? Now see, see, earth is divided or you can draw small circles like this. Correct?
do you see do you imagine that's like see if this is the greatest possible circle correct if you draw small small circles like if you draw another circle like this this will be smaller smaller smaller smaller smaller and then you reach north pole correct so these are called as latitudes correct now latitudes are parallel to equator latitudes are parallel to equator understood correct now what is the function of latitudes see from equator if you take north pole the angle will be 90 degrees correct so the highest latitude possible is 90 degrees north and 90 degrees south correct from the equator let me draw equator with a black color let's say this is the equator correct Now, if you go up, this will be 10 degrees north. So this latitude Entirely is 10 degrees north. This is 20 degrees north, 30 degrees north, 40 degrees north, 50 degrees north, 60 degrees north, 70, 80 and at last 90 degrees north.
90 degrees north means north pole. Is it true or magnetic? That is true.
Understood. Correct. So these are called as latitudes because they are parallel to equator.
They are called as the original name is parallel of latitudes. The original name, the bookish name of latitudes is parallel of latitudes. Am I clear? Am I clear? Now, can someone say what is the meaning of the word datum?
Reference. Very good. Datum means reference.
Correct. Now, equator acts as the reference for latitudes. Correct.
Now, see, if you are here, if you are standing here, you are standing at 40 degrees north latitude. That means from equator, you went 40 degrees up. Correct.
Same way downwards. If you go, this is 10 degrees south, 20 degrees south, 30 degrees south, 40, 50, 60, 70, 80, 90. Correct. So if you are here, that means you are at, let's say, 45 degrees south latitude.
Understood. So, from where you are calculating, you are calculating equator as your reference. So, that is why equator is the datum or reference for calculating latitudes.
So, equator is datum or reference for calculating latitudes. How many of you understood these concepts? Correct.
See all the circles will be around like this behind also it will be there. Correct. like this like this like this understood now do you see this picture correct so this is the equator this said this is the greatest possible circle which is perpendicular to the poles correct this is the equator this is the equator now what is this line called as the circle latitude latitude what which latitude is this see 10 degrees is it north or south north north this one 20 degrees north 20 degrees north this one 30 degrees north 30 degrees north great 40 50 60 70 80 90 correct now this one this line 10 20 degrees south very good 10 20 degrees south correct now imagine umkar you are standing here you are standing at 30 degrees north see india is i mean delhi's latitude is 28 degrees north probably you are uh in chandigarh okay now from chandigarh you travel like this correct you want to reach a place here let's say this is a place named by um let's say it is the name of this place is x correct now how many latitudes or how much latitude is your travel degrees 50 degrees that means you travel here 10 degrees 20 degrees 30 degrees 40 degrees and 50 degrees correct so this is called as change in latitude or difference in latitude correct so that is called as chi long sorry chi lat chi lat means change in latitude it is also called as d lat it is called as difference in latitude and if you fly from us now if you go there and say chi long they will look look at you kind of awkward here what is the slang okay when you go there you see long right she'll make it stylish she long she lat she lat latitude you mean lat means latitude of course i'll teach you she lat and d lat all d long and d long also correct so pronounce chs she she lat or okay not in my class i will not allow this i'm like i'm not going out out anywhere it is chill at Delayed understood now You are here 60 degrees north correct? You want to go to south pole what is your DLAT from 60 degrees north you want to go to south pole? 150. From 60 you are going to equator first?
Yes. Correct. This would be how much? 60 degrees.
Correct. From equator, you are going to South Pole. This will be how much? 90 degrees.
90 degrees. 60 would be 150 degrees. Correct. How many of you tell your answer is 150? Raise your hands.
150 South. Very good. See, you are going towards South Pole. Understood.
So, your chill out is. 150 degrees south understood am i clear on this am i clear on this okay now manthan give me a latitude 55 north from 55 north where do you want to go 25 south 25 degrees south what is the d lat or she'll add it is out this is uh the earth this is the equator correct so 55 degrees north is here circle so from this circle i am going to 25 degrees south so i'll travel to equator 55 plus from 25 more 55 25 so 10 80 degrees so 80 degrees i am traveling In which direction I am traveling? Towards south. So, 80 degrees south is my answer.
Correct. Now, if you have to travel from 20 degrees south to 80 degrees south, what is your D-Lad? 60 degrees south. 60 south. 60 south.
60 south. So, you are traveling from 20 degrees south to... 80 degrees south correct you are traveling south correct it is not don't think you're 55 and 25 added it will always be adding correct some people will teach you like here if it is same hemisphere you subtract it is different no no no no don't remember bullshit always imagine a sphere correct you will always be correct okay if you understand the concept so from 20 i will travel to 30 10 40 10 10 and then i'll reach 80 so 80 minus so total this is 80 and this is 20 if i want this 80 minus 20 that is 60 degrees i'm traveling in which direction i'm traveling south 60 degrees south how many of you understand chillat okay next you see here just because to make things easier if you allow me i'll draw earth like this north pole here and the south pole here if you allow only correct shall i draw correct see actually earth is like this but because i i want to make things easier i will make the axis right so this is my polar axis understood now If I draw a line, if I draw a greatest possible circle like this from North Pole to South Pole, correct. Now, can I say these two are exactly opposite? For example, I'll take the globe.
okay do you see this red line do you see this red line correct now if i continue the red line on the opposite side like this correct that means they are exactly opposite to each other right do you see correct now if i keep you like this you can just see the blue line here correct and you can just see the red line here correct now that means They are exactly opposite to each other. Now, see, this is the equator. Correct. This is the equator.
Correct. Now, if I chop this, if I chop this, correct. Now, and if I look from the top, correct, will it look like this? this is north pole i have chopped it correct these this is the equator correct circle of equator now see here you can draw a great circle like this also you can draw a great circle like this also you can draw a great circle like this also understood correct now these are the longitudes correct longitudes join north pole and south pole correct see how many of you say let's say this is one longitude correct i will take one longitude first here how many of you say This longitude is a great circle. It is half of a great circle.
Very good. See, this is half of the great circle. Correct?
The longitude opposite to it will complete a circle and they both are a great circle. Understood? So, by definition, longitudes... the actual word for longitudes is meridians meridians are semi-grade circles semi-grade circles correct they join what north pole and south pole understood how many of you understood this here tell me which country invaded india Britain. Britain.
Correct. Which is the capital of Britain? London. London. Here, see, these are the people who traveled first.
Correct. So, here, if this is inland, correct, there is a place called Greenwich. Greenwich is the place, it is considered the first traveling happened from there.
Correct. Now, when they used to move like this correct they used to calculate like this here i am moving like this correct so i have i have reached 10 degrees towards east i have gone 20 degrees towards east 30 degrees towards this 40 degrees to assist 50 degrees towards east correct understood so they used to take green which as the datum or reference to measure longitudes Understood. So, Greenwich or the meridian which passes through the Greenwich is called as Greenwich meridian or it's called as prime meridian. At prime meridian, it is considered 0 degrees east or west. Now, if you go east from prime meridian, it is 10 degrees east, 20 degrees east, 30 degrees east.
40 50 60 70 80 you will reach 90 degrees east and somewhere here you will reach opposite to that greenwich meridian anti-meridian of greenwich that means the 180 degree opposite meridian of greenwich correct that will be 180 degrees east now if you go west 10 degrees west 20 degrees west so on and so forth till 180 degrees west understood correct now If you take any meridian, correct, if you take any meridian, its opposite meridian is called as anti-meridian, correct. So, meridian, if you take the opposite to it, opposite means at 180, less or minus 180 degrees, it is called as its anti-meridian. can i say meridian is a great circle is it correct no correct a meridian and its anti-meridian will be a great circle and i should now see do you see the lines correct meridians correct and their anti-meridians on the other side understood now let me show you a better diagram Do you see this is the north pole?
This is the south pole, correct? If you imagine this is the prime meridian, prime meridian I said zero degrees east or west, correct? Now, this is east direction, this is west direction, correct?
Now from here, if you go 10 degrees, this is 10 degrees east, this is 20 degrees east meridian, 30 degrees east meridian, so on and so forth. correct now tell me total number of longitudes what is the maximum number of longitudes that can be that can be drawn 180 no 180 degrees wait wait this is earth north pole do you see correct this is also longitude this is also longitude longitude longitude correct now if i see the earth from the top top view correct this will be the north pole like this see do you see the hole correct now let's say this red line is the prime meridian do you see the red line do you see the red line this red line is the prime meridian let's say okay so it is like this correct so understood this is zero degrees east or west i'll show you correctly do you see this was earth it was rotating like this correct now i am looking there from the top you also look there from the top correct now if red line this red line is the primary region it will be zero degrees east or west correct now from here if you go east 10 degrees, 20 degrees east, 30 degrees east, so on and so forth. Correct?
So, 10 degrees east, 20 degrees east, 30 east, 40 east, so on and so forth. Here, it will be 90 degrees east. Correct? Here, 100 degrees east, 110 degrees east, so on and so forth.
Now, if you take the opposite to prime meridian. Correct? So, it will be how much? this angle will be how much generally 180 correct so it will be 180 degrees east am i clear east or west correct are you able to imagine the earth seeing from the top correct now if you go west this was east correct if you go west correct it is 10 degrees west 20 west 30 west 40 west on and so forth here it will be 90 west correct here the exact same thing will be 180 degrees west also that is why it is called as 180 degrees east or west correct now tell me c long that means change in longitude we will take two longitudes okay i will take this longitude which is this longitude This is the primary 10 degrees, you're from the primary then you're going east by 10 degrees, correct. So this is 10 degrees east, how many of you agree with me?
Now if you have to go to from 10 degrees to let's say this longitude. You see, this is 10 degrees east. From 10 degrees, you are going to which longitude? 40 degrees east. Correct.
What is your D long or G long? 10 to 20 also. 10 to 40. From 10 degrees, you are going to? 30 degrees. 30 degrees east.
40 degrees 30 degrees 30 degrees answer is wrong better answer i want east very good so you're traveling 30 degrees here you're traveling towards east correct here see from 10 degrees east this is the same longitude correct if you travel 30 degrees in this direction you will reach 10 degrees to prime meridian and then 10 more degrees 10 more degrees so you will reach 20 degrees west understood So this Geelong is 30 degrees West Geelong. This is 30 degrees East Geelong. How many of you understood? Correct.
Now you're going from this point. You are standing in Africa here. Sorry, South America here.
And you are going to this point. Okay. Now see, can someone say What is the latitude of this point?
Latitude means from the equator, where is it? 10 degrees, 20 degrees, 30 degrees. See all this latitude is 30 degrees south, entire small circle around the earth.
So this fellow is standing on 30 degrees south latitude. Now what is the longitude of this place? From the prime meridian, 10 degrees, 20 degrees, 30 degrees. 40 degrees 50 degrees and 60 degrees see this is the 60 degrees longitude of this place correct so the coordinate of this guy is 30 degrees south and 60 degrees west correct from the prime meridian he went west correct this is this this would be east correct from the prime meridian he went west so the coordinates of this person is 30 degrees south and 60 degrees west how many of you understood this correct now tell me the coordinates of this guy no no don't tell give me the answer in the chat be fast i want to see how many of you really are the coordinates of this guy this is the point where he is standing 30 not 20 east yeah i don't know give it in the chart i want to see who all understood and who already did okay so manthan your answer is correct okay i'll answer i'll ask one more question see that means from the equator this is latitude correct latitude 10 degrees 20 degrees 30 degrees so 30 degrees north latitude and because he is in this circle in this small circle correct now from the equator he is from the prime meridian he is 10 degrees east 20 degrees 30 degrees north and 20 degrees east is the coordinate of this person how many of you understood correct now let's say this is point x this is point y correct now if this person has to travel from x to y correct now calculate qilong and qilat calculate qilat and qilong give answer in the group sorry in the chart here in the chart everybody's answer was correct actually for first question give qilat and qilong if this person has to go here and here see this person has to go to this longitude and then here correct or this person has to go to this latitude 30 degrees north and then like this let's calculate the chi lat and then calculate the chi long Varun, your answer is correct.
Very good. Type in fast guys. Manthan, your answer is correct.
sujali your answer is exactly correct azhar darwin onkar see i am here correct now i have to go to this longitude which is 20 degrees east correct this longitude so i will travel to the prime meridian first which would be how much 60 degrees correct i am at 60 degrees west so i will travel 60 degrees which direction i am traveling here east east correct if i travel 60 degrees i will reach here correct yes but i want to go to which longitude 20 degrees east correct 60 plus 20 plus 20 degrees right both i am traveling in east direction correct so 60 plus 20 would be 80 degrees towards east this is my chi long correct from 80 degrees sorry from here which is 20 degrees sorry 30 degrees north so the south correct 30 degrees south this is the longitude you So, this is latitude 30 degree south latitude. I am going to 30 degrees north latitude correct. So, till the equator is 30 degrees and from the equator it is 30 degrees correct. Total how much 60 degrees?
60 degrees I am traveling in which direction towards north or south? North. Towards north correct.
So, this is the she lat 60 degrees. towards north and 80 degrees towards east are the chillat and chillong for this person to travel so north is chillat right yeah chillat change in latitude okay i'm changing my latitude from 30 degrees south to 30 degrees north how many of you understood this right answer understood okay I want answers for these three questions. All answers in the group.
All dancers in the group only. Thank you. You are not audible.
i'm sorry i'm sorry i'm sorry so i'm going from 85 degrees south to 10 degrees north so this is 85 and then 10 85 plus 10 95 i'm going towards which pole north pole correct so this answer is 95 degrees north here everybody gave the same answers and everybody is correct am i clear okay Now see, here I will tell you a trick to calculate Qilong. Qilong, they will try to confuse a lot. For example, shall I give you one example? What is the Qilong between 160 degrees west to 90 degrees east? Calculate.
160 degrees west longitude to 90 degrees east longitude. Give me the answer. I will show you a simple method how to do this.
How to imagine things. 250 degrees east, sir. 250 degrees east by Unkar. Okay. Others?
110 degrees east by Azhar. 20 degrees, sorry, 110 degrees east. East by Sujan. Varun, Mantan? Same, sir.
Varun, same. Sorry, Mantan, same. 110 degrees east.
One west, two east. 110 degrees east. I'll do it.
see if you take this earth and do you see the silver line which is your equator correct now this is your pole north pole correct always see the earth as i see correct when they ask qi long correct see the earth from the top like this correct now equator is here correct i'll draw equator here like this you correct that is equal now where is north pole north pole is in the center like this correct so this is my north pole now this is the prime meridian correct so prime meridian is here this is zero degrees east or west right this is 90 degrees east this is 180 degrees east or west correct this is 90 degrees west correct imagine you are seeing the earth from the top like this top view of earth understood now see i have asked chi long between 160 degrees west and 90 degrees east correct so 160 degrees west will be here 90 degrees west uh maybe 100 degrees west 145 degrees so 160 degrees west will be here so this is my point a correct i'm going to which point 90 degrees 90 degrees east is here understood see let this be my point b correct that means i am traveling on earth like this in this direction okay now see from prime meridian this is east and this is west correct see if i am moving on earth from here to here i am traveling east or west? East. If I move further like this, I'm traveling east or west?
East. If I travel here, is it east or west? East.
If I travel like this, is it east or west? Still east. Still east because I'm going in east direction, correct?
For this guy who is standing here, This will be his east and this direction will be west correct. So I'm still traveling east understood So this is east direction, right? Now, for example, if you are at let me take a blue color Correct if you are here and if you go like this, you're going obviously West and I should so this is your best direction if you go further this is further west west here this is west correct here this is west understood so now tell me if you are going from point a to point b you are going east or west we are going west west correct because if you travel like this this is east But you are traveling like this opposite to this. So this is West.
How many of you understood East or West? Correct. And always look there from the top.
Correct. So everybody of you is wrong. Understood.
Now I want answers for all this four. Everybody don't tell it out. Either. it should be given in the chart or in the whatsapp group group only no personal messages only group so what is the answer for that sir it is from 160 you go to anti-prime meridian which is 20 degrees correct and 90 more 90 plus 20 It is 110. So, you are going west direction. 110 degrees west is the answer.
Too fast, too fast here. I am hungry. Varun already gave the answer. Very good. Same answer.
If two answers are same, probably both are correct. Others, Mantan, Omkar, Azhar. Okay, Varun. Guys, you are taking too much time. Okay.
Everybody take a look at the screen. I will explain. Here, from where I am looking towards the earth? From which pole?
North pole. Correct. North pole. I am looking from the top view of earth.
Correct. So, if this is the earth, I am looking like this. so this is my zero degrees histograms correct let me show you on google earth there why not correct let me show you my view of well for these questions do you see you see this is the equator okay now it is actually inclined like this but i'll take it straight like this now do you see 10 degrees north 20 degrees north 23 sorry 30 30 degrees north 40 50 north so on and so forth now do you see the longitudes correct so this is the prime meridian correct this is the anti-prime meridian correct So primary is zero to zero to anti primary and it will be 180. Correct. This if you travel like this, you're traveling.
If you travel like this on earth, you're traveling west. Correct. So whenever they give me longitude questions, I'll try to look there.
Like this. So what was the first question they asked? 30 degrees east to 70 degrees east correct now where is my 30 degrees east so if i rotate the earth and i generally make primary at the bottom so that it will always be easy in one go correct 30 degrees east to which one 70 degrees east yes so 10 i'm going towards east correct 20 east 30 east 40 east correct so the answer to this question is 30 degrees east this is 90 degrees east correct to 70 degrees east right i am going east how many degrees 40 50 60 70 correct sir what if we look from the south pole don't imagine two things okay if you want to follow from south pole you follow south pole completely but better use my imagination i mean this is very easy towards south pole it will look like this opposite sir will be opposite clockwise will be this will be east and this will be opposite to your convention correct you can look at the earth like this also but you don't look at the earth like this correct you always imagined the earth as south pole as bottom and north pole as top understood clear everyone now coming to the second i'll do this last question 130 degrees west to 140 degrees east.
This is 90 degrees west. So let's say here it is 130 degrees west. This is 90 degrees east. Let's say here it is 140 degrees east.
This is anti-prime meridian 180 degrees east or west. I'm going from point A 130 degrees west to point B 140 degrees east. till the anti-prime gradient how much i'm going 140 150 160 170 180 so 180 minus 130 would be 50 degrees right from 180 to 140 i'm going how much 170 160 130 sorry uh i mean 170 160 150 140 so i'm going 40. correct now if i go in this direction which is this direction West. West.
Great. So, I am going west. I am going west.
So, what is the total? Shillong 50 plus 40 would be 90 degrees in west direction. 90 degrees west is the total Shillong. How many of you understood?
Sir, I am getting confused with that west or east. No. Sir, yeah, the last. Sir, but the 140 degree east means it should go anti-clockwise, no? If you're looking from north, if you're going anti-clockwise, it would be east.
If you're going clockwise, it would be east. Wait, I'll explain it in a better fashion. Let's assume you're standing here at my cursor. correct if i take a screenshot i can probably write on this correct so if i am standing here okay anywhere i go like this this is east anywhere i go this is west correct so here it is this is west and here it is east correct because this entire thing is east this entire thing is west from primary okay now see tell me if you are standing here this is east correct now if i do this correct and if i take my prime meridian here at the bottom correct sorry prime meridian should come now this is 0 degrees east correct this is 10 degrees east longitude 20 degrees east longitude so on at this direction is east correct so if you go this this is east so this is east correct if a guy is standing here for him this direction would be east and this direction would How many of you understood?
Correct. For a guy standing here, right for him, see this is East, this is East, correct? Still, this direction would be East, right? And this direction would be West. Correct?
Now the earth is rotating west to east, and this rotating when you see it from the top and a clockwise, correct? Now, that's why he for this guy, If you take, if I stand like this, this is west, sorry, east. Let's assume this is my right hand and it is east.
Now my right hand, if it comes here also, it will still be pointing east. Understood. So this direction is east and this direction would be west anywhere. How many of you understood this convention?
Not convention. Yeah. Convention. Clear everyone.
Ongar. Done. Now, Ongar and everyone, I want to do the third question. 20 degrees east. Let me check.
This is 0 degrees east or west and I am seeing the earth on the top. This is my north pole. This is 180 degrees east or west. So, I am going from 165 degrees east to where?
175 degrees west. 165 to 180 it will be 15 from 180 to 175 it will be 5 so total i am traveling 20 degrees in which direction i am traveling east east correct 20 degrees east is the answer how many of you understood correct see don't remember anything just imagine it correct play with google earth today okay understood i mean how did you get get those latitudes and longitudes in the earth how did i how did you get those latitudes and longitudes those 10 20 degrees 30 now you showed us the earth see the earth generally is like this if you see correct this is the equator correct so these are my this is the equator these are my latitudes you not that sir like what are the settings to get those latitudes and longitudes okay in the google earth yeah yeah okay fine that is the last answer no uh yeah if you want to leave it is almost you can leave okay and i think um in settings you have to go and apply some i do did something here i don't know i'm a glare on this but am i clear on this characters now here i want you guys to do an experiment okay who who wants to do the experiment raise your hand Darwin, I'll give this chance to you. Darwin, take, you know, what is it? Take what is a jug, you know, jug or take a bottle, take a bottle.
Okay. Imagine a bottle. Correct. Now hold it, hold it. Okay.
Okay. So this is like a bowl of bowl or a jug. Correct.
Now pour water in it. Pour water in it. Pour here.
Okay. Okay. Is it filled?
Yeah. Okay. Give some gap.
If not, it will fall on your nose. Don't, don't. Okay.
So now there is water in your jug. Okay. In your bowl.
Okay. Now take a piece of paper and throw it. What will happen to the piece of paper?
It will float. It will float. Now take a small stone and throw it, throw in it.
What is happening to the stone? Show us here. Show us. We are not able to see. Okay.
It's going inside. Huh? It is going down.
It dipped inside. It dipped inside. Correct. Why? Because the density of the stone is more.
Correct. Now see, if you take Earth, 23.5 degrees north is called as Tropic of Cancer. 66.5 north latitudes. These are latitudes.
It's called as Arctic Circle. Correct. These are the names given to those latitudes because they are very important in climatology of India.
Correct. 23 and a half South is given Tropic of Capricorn. 66 and a half degrees South is given as Antarctic circle.
When I went to exam here 23 and a half is like Cancer or Capricorn. I was always having, I was very confused here. See how many letters Cancer has? One, two.
3, 4, 5, 6. Capricorn has 1, 2, 3, 4, 5, 6, 7, 8, 9. Here more weight of the stone dipped inside. So Capricorn came down. Understood. Arctic Circle, 66 end of north.
See Arctic. 1, 2, 3, 4, 5, 6. Antarctic. 1, 2, 3, 4, 5, 6, 7, 8, 9. Correct.
More number of letters. It will come towards south. Understood. So don't confuse. These are.
some significant latitudes, significant latitudes, 23 and half North Tropic of Cancer, 66 and half North Arcturic Circle, 23 and half South Tropic of Capricorn, 66 and half South Unductic Circle. Am I clear? Am I clear? Here, how many of you seen pilots carrying the small globes in the airport and taking a small thread and measuring here i am going from delhi na i'll go to hyderabad did anyone of you see them carrying globes and all huh no no what do they carry we carry charts correct so this charts now in this chart see if you take a globe now see this is the north pole correct now if you take a chart it will be like this longitude will be like this and these are latitudes correct see in a chart this is also north pole this is also north pole this is also north pole this is also north pole it's also not correct this is south pole this is south pole south pole south pole south pole correct probably this is an equator correct this is equator understood that means see it is very inconvenient for the pilots to carry globes that's why we made charts correct And of course, it is not very easy to make charts. There are different kinds of charts.
One which I am showing is called as Mercator chart. In a Mercator chart, the latitudes and longitudes are perpendicular to each other. Correct. There are many North Poles on the Mercator. Every end is a North Pole.
Many South Poles. Correct. So this kind of representation of latitudes and longitudes.
Latitudes and longitudes not on earth on a map on a map or a chart see on real earth they are like this right but for making it easy to read maps and charts they made it like this for example this is a Mercator chart of course there are Lambert chart latitudes will be like this and longitudes will sorry longitudes will be like this and latitudes will be like this correct different types we will read them in detail correct so that a representation of latitudes or longitudes and on a map this is called as a gratitude make clear so what is the definition of gratitude what is the definition of gratitude latitudes and longitudes when drawn on a map or a chart there will not be any exam without this question what is a graticule they will say network of latitudes and longitudes you will go for it absolutely wrong last option would be network of latitudes and longitudes on a map or a chart that is the correct answer correct on a map or a chart underline this do something something key you don't forget it in exam because the first option would be network of latitudes and longitudes and you will always go for that option am i clear on this everyone azar suzel yes sir okay fine here uh tomorrow bring your scientific calculator okay so what is a scientific calculator it will look like this it will look like this it will cost around 500 rupees or less yeah like that that too latitude or longitude on map or chart that's a map or a chart not on earth okay okay on a map now it will look like this this is very much needed because tomorrow i'll ask you to do chi long and chi lat in minutes and seconds also correct not only in degrees this is minutes and of course i can divide it into seconds that division i will teach you tomorrow here tomorrow will be the most interesting class which you ever heard in your life believe me okay it was most interesting to me learning about how you really travel on the earth correct i have showed you like this correct you are traveling from here to here correct this is the chelat and chelang do you travel so long no you will take a shortcut correct now what is the shortest possible thing correct so that shortest possible distance i'll be teaching you tomorrow which is very awesomely entertaining correct so i'll see you tomorrow bye bye guys i'll send the notes in the group fine bye