Indian Monsoon System Overview

All right. Welcome all to Plutus IS. And today, we are going to start with Indian monsoon. All right. In the previous live session in which we have met, we have discussed about different issues. I don't like it. Okay, I will try it. Should I start or not? You can start by looking at the comments. I will have to open the comments on that, right? Yes. Welcome all to Prutus IS. Today we are going to discuss about Indian Monsoon. In the previous lecture, live lecture that we have done, we have engaged so many people and thank you so much that so many people, viewers were there at that time. But what I thought at that time, apart from the online students which are already present in the class, the viewers who are watching on the YouTube, they should interact much more because I'm constantly watching the, I'm constantly reading the comments. that this is a live session that you're going you're watching and if you want to interact in mid or middle of the session then you can definitely do that i'll be responding to each one of you as much as it is possible right so indian monsoon is very very important from the prelims and the mains perspective and before starting this okay so before starting this i will also like to give some of the fundamentals of the geography which are required to understand the Indian monsoon because I want to keep this session so that everyone, everyone who has even not done anything related to the winds or the seasonal winds or anything related to high pressure, low pressure and people who have already done anything related to climatology that's excellent but people who are not come from that background maybe they have not covered that in their syllabus. they can also understand right all right online students uh very good evening right keep on interacting with me okay right so indian monsoon why it is important i told you because majorly how many questions comes in means at least two questions are expended expected or one question is expected out of it right and in freelance you expect a question definitely a question from it now conceptually you are required to be sound in this reason being lot of times UPSC throws a conceptual question at you which you might not be able to solve if you have not done the concept very very clearly okay first draw the diagram okay i hope that everybody knows how to draw indian map if you don't know you will just get a practice of it with consistent drawing okay because of the lack of space i'm not drawing so i have to show a area below the equator okay all right in june or you can precisely say may and june right the sun is overhead or sun is Giving the maximum insulation where in northern hemisphere How has the maximum insulation there ahead northern hemisphere? Right it is giving maximum insulation in northern hemisphere Why as you know the northern hemisphere what happens in May June, right? What is starting coming in your summers right as summers are approaching what will happen? the Sun will move to it will move to northern hemisphere, right? Once it moves to northern hemisphere, there would be what? There would be direct insulation. That means the area above the equator, which is northern hemisphere, will be more heated up as compared to the southern hemisphere, right? Anything, any doubt regarding this till here? Any doubt? So, what this phenomena is known is I hope that you all have done the different seasons, right? you have done different seasons how many seasons we have summer winter and we have equinox right spring and autumn right so all these seasons that we have in particularly i am talking about the summers where the sun is moving above the equator and it is giving more constant sunlight insulation is being there in the northern hemisphere so what will happen this will become a region of low pressure this will become a region of low pressure and in southern hemisphere it will become a region of high pressure okay what is low pressure relatively high relatively low right because here the insulation is not going to be much more so what will happen in that as i have told you earlier also and for the people who are just going to this topic for the first time please like don't Wind always blow from wind always blow from high pressure to low pressure This is a universal rule that you have to remember that it always blow from high pressure to low pressure Which means we are talking about surface winds. This is the surface wind that I'll be talking about It is it is moving from high pressure to low pressure. Please write down make a note and write down in your notebooks. Winds always blow from high pressure to low pressure. So once the winds are blowing from high pressure to low pressure, this is known. This is coming from southern hemisphere. This is coming from southern hemisphere. Once it crosses, I'm taking a different color pen. Once it crosses the equator, what will happen? Do you think the wind direction is going to be like this as I have shown it to you? Okay, for the people who cannot see the board clearly, I'm drawing it here. So consider this as the Indian map. This is equator. Okay, the wind is coming from this side, right? I've shown the wind direction of the winds like this. Do you think the wind direction is going to be like this straight? No. Reason B? Tell me the reason. Online students, what is the reason? Because I have told you that there is a constant force which is working on the wind which is known as Coriolis. Coriolis force, right? Since the Coriolis force is working, what will happen? It will change its direction, right? It will change its direction. So, once it moves towards the equator, what will happen? In the northern hemisphere, the Coriolis force, where it gets deflected? Coriolis force? moves towards right. It deflects towards right. Where? In northern hemisphere. For example, this is the direction of the wind in the northern hemisphere. How it will be deflected? Right or left? It will be deflected? Right. Right. In the northern hemisphere, please write down northern hemisphere, the wind is going to get deflected towards right. Towards right. And in southern hemisphere in southern hemisphere due to Coriolis force due to Coriolis force wind is going to get deflected towards left right okay so since the wind is coming from here right Now it is going to deflect in this direction. Can you tell me the direction of this wind? Can you tell me the direction of this wind? What is this direction? Yes, Sanjana, you are right. What is the direction of this wind? No, what is this direction called? What is this direction called? It is southwest. It is south. So, can I call it as a south west winds, right? Can I say that the south west winds are coming from the and they are hitting where Indian subcontinent, right? They are coming and hitting Indian subcontinent. Now, once this wind comes, what will happen? There would be two branches of this wind. Your southwest wind will have how many branches? Two branches. It will have two branches. One is Arabian branch and another one is your Bay of Bengal. branch, Bree of Bengal branch. Okay, so when you talk about that monsoon are approaching, hum kya baat karte hain ki jab monsoon aa raha toh sabse pehle kaha pe hit hota hai? When we have seen news channels right in May or in June, you talk about that arrival of monsoon right. So we talk about where it is hitting first, so where it is expected that the monsoon will come. It is in Kerala. The first monsoon comes in Kerala. Then your Karnataka and other region. Then Mumbai. Right. And then Mumbai means Maharashtra. Right. So it will come in different states. So but first it comes where? In Kerala. If we talk about this coastline, I'm talking about particularly this area of India, it will come to Kerala state. Right. what will happen next? What will happen next? Right? So what will happen? Then it will move parallel, this will move parallel and this will move towards your north system area. What is your north system area known as? Your how many states? Your Meghalaya, Manipur, Tirupura, Arunachal Pradesh, Assam, right? So it will move and it will hit this area. Once it hits this area, there will be a rainfall in northeastern. Why? Because of Bay of Bengal branch, right? But Arabian branch goes parallel with this area. What is this area known as? Rajasthan. It goes parallel to the Rajasthan. So please understand this concept. if the winds are not going to... get what? They are not going to get hit, right? You need to hit a place, right? In order to get a rainfall, but it is just running parallel. It is running parallel to this area. So what will happen? There will be no rainfall here. We are in Rajasthan. There are other reasons also why Rajasthan is not having a rainfall. But one of the reasons why I mean not having a rainfall means less amount of rainfall. It is experiencing minimum amount of rainfall. in an annual year. So why it is happening? It is happening because one of the reason is this and another reason I will discuss with you after few minutes. So this is one of the reason why Rajasthan is not experiencing rainfall because of the Arabian branch. Reason being it runs parallel where towards the near this area okay any doubt in this please have a look at all the concepts and let me know if you have any doubt Yes, people who are watching online, I mean the viewers on YouTube can also interact in between of this lecture. I'll be constantly reading your comments. Okay, online students, is it clear to you? Please raise your hands or use the chat box. Alright, done. I'll make you write everything, don't worry. Okay, next. So this is again, I'm drawing this area. There will be rainfall in north eastern region, right? Now, This Bay of Bengal branch moves towards interior of the earth, interior of the Indian subcontinent, right? It moves towards the interior of the subcontinent. It moves, it deflects towards interior of the Indian subcontinent. subcontinent. Can you tell me the reason why? Can you tell me the reason we have done that? We have already done that. We have discussed about that jet stream. I'm giving you the hint. Yes. can you tell me this is the one of the branch right it is going towards this this is bay of bengal this is Now tell me, ideally what should have happened? This branch should have gone and it should have crossed the Arakan mountains range and then it would have gone to other Southeast Asian here, different countries, right? Myanmar, right? But it does go there also, but why it is deflecting back inside of the Indian subcontinent? What is the reason behind that? because of the trade means maybe. Sanjana, trade means are not responsible for it. I gave you the hint that I'm discussing. The hint that I gave to you is a jet stream and many times while I was going through that lecture, I have discussed that this jet stream is having a huge role in Indian monsoon. It is because of the tropical easterly jet streams which move from east to west has a huge role in deflecting the winds inside the Indian subcontinent. What will happen? See, this wind ideally should have gone like that right but because of this jet streams because of tropical easterly jet streams, the winds are coming inside and this is majorly responsible for bringing the rainfall in the states which are in the interior part of the Indian subcontinent. What they are doing? They are picking up the moisture from the Bay of Bengal, what sea? They are picking up the moisture from here and once they pick up the moisture from here, they will bring rainfall in the north eastern area and then half of that will come inside. Why? Because of the tropical easterly jet streams. Once they come inside, what they do? They bring... huge heavy rainfall right and as they move they keep on moving right as they move what will happen this branch this bay of bengal winds what they will do their bay of bengal branch this will loosen the moisture It is responsible for the rainfall. It will just responsible for the rainfall when there will be moisture present in it. Agar wind mein moisture nahin hoga because they are coming on the land. Now they are not having enough what? Moisture present as they are moving inside. So their moisture would be not enough to bring rainfall in which part? In the Rajasthan area. Right? How many of you can understand? than this concept or if you have any doubt please ask take two minutes just go through it and ask Write down. Just start the Indian monsoon. Write down the heading Indian monsoons. Yes, Rakshath, Achul, Harshika, Sanjana, Ruhans, Suraj. Please ask if you have any doubt. It's amazing ma'am because I can't take the life. I have watched all the recorded lectures. Good Sanjana. No problem. Yes, sometimes in between we are conducting the live lectures of the ongoing batches. right? So then you can watch from there, okay? Write down, monsoons are seasonal winds, monsoons are seasonal winds which reverse their direction, which reverse their direction, monsoons are seasonal winds which reverse their direction. with the change of season. Write down, full stop. The monsoon is a double system of... Please let me know if my speed is too fast. Write down. Write down. The monsoon is a double system of seasonal winds. Monsoon is a double system of seasonal winds. which, then write down, they flow from sea to land during summer. They flow from sea to land during summer and from land to sea during winter. Write down. They flow from sea to land during summer. Have you not seen the diagram? What do we call this as? When there is winds coming from sea to land, we call that as... onshore. This is known as onshore winds and when they are from land to sea, this is known as offshore. Always remember, right? Offshore is land to sea. Full stop. India receives southwest monsoon winds. India receives Southwest monsoon winds in summer. Monsoon winds in summer. and north east monsoon winds in winter. Please underline both. Please underline south west monsoon winds in summer and north east monsoon winds in winter. Now write down factors responsible sectors responsible for southwest factors responsible for southwest monsoons right on the first point intense heating of tibetan plateau intense heating of tibetan plateau Please understand this point carefully. See, where is tibbath? Here. This tibbath is an elevated area or elevated plateau. This is an elevated plateau. Elevated means, thoda uthava. So it's an elevative. It is rising above sea level. The height between the sea and the land is quite flat. Kitna? Flat to jitna. So in summers, or you can say in the month of May, what will happen? It will get too much of insulation. And it will create a region of low pressure. It will create a region of low pressure. Right? So that's why this is also one of the major factor why it is attracting what? Southwest winds. Why it is attracting southwest winds? Why? Because this is an area of high pressure. And this has become an area of low pressure. When this has become the area of low pressure, it will attract. winds towards it. Intense heating of tibetan plateau. Tibet is an area which is elevated. and in summers and in summers, the tibetan plateau gets the tibetan plateau gets intensely heated. Thus forming the region of low pressure thus forming the region of low pressure leading to strong vertical air currents Right on the next. Tropical easterly jet. Tropical easterly jet. write down in the short form you can write tej also also known as african easterly jet also known as african easterly jet comma set in along 15 degree north latitude of the withdrawal of westerly jet streams. Westerly jet streams. What do you mean by that? See, your tropical easterly jet stream, this one, I have given you 15 degree knot. But do you think it is fixed? It is not fixed. Because tropical easterly jet streams, the position of that can also vary. For example, this year the tropical easterly jet has come just above the Odisha, right? But it can also come like this. So, what will happen? Because tropical easterly jet is coming here, so it will bring what? More rainfall in the southern India as compared to central and northern India, right? Once it is lower in the position, right? It can also happen that this in the same area it can come right but i cannot fix the latitude like that on an average i have given a latitude to you that is 15 degree dot but it can be more in the southern area then it will be responsible for bringing heavy rainfall in the this area right or it can also move a little upwards right depending upon different factors the position of the tropical easterly jet streams can change right so write down taj also known as african easterly jet comma sets in along 15 degree north latitude after withdrawal of westerly jet stream written till here right first off this jet streams helps in the This jet stream helps in the burst of the monsoon. This jet stream helps in the burst of the monsoon in India. It leads to burst of the monsoon in India. As it helps in strengthening the... as it helps in strengthening the south west winds. Next write down permanent high pressure cell. These points are extremely extremely important for the prelims because in prelims they will ask there's a question will be given that which all factors are responsible for southwest monsoons. Then four options will be given to you and if four options will be given to you then you have to select one. If you will not have the a conceptual knowledge then there is a big chance high chance that you might pick against wrong option right now write down permanent high pressure cell in the South Indian Ocean. In the South Indian Ocean. Yes, Rakshata, I'll address your query just after dictation. Okay, write down. A permanent high pressure cell exists east of Madagascar, east of Madagascar. Where is Madagascar? Africa, right? This is What? Madagascar. Right? This is Madagascar. Okay? Below your equator. So in which region basically it is? southern hemisphere. I told you because the sun is over northern hemisphere. So, it will experience what? High pressure. It's a high pressure zone. So, what my statement is saying that east of Madagascar what will happen? there will be what permanent high pressure zone what you have written so far what do you have written so far okay comma approximately at 20 degrees south over the indian ocean over the Indian Ocean. full stop the intensity and the intensity and position of the high pressure area the intensity and the intensity and position of the high pressure area significantly affect the Indian monsoon. Significantly affect the Indian monsoon. Next write down subtropical jet streams. Subtropical jet streams. How many of you remember the subtropical jet streams? We have just covered the topic. recently subtropical geltring. These are also known as with western disturbances. These are also known as what? Western disturbances and since they are known as western disturbances, what will happen? They are responsible for they are also responsible they also contribute in Indian monsoon making differently we'll come to that okay they have a huge role in Indian monsoon as well but we'll come to that Abhi Kili please understand this so this wins all right I'll explain here only see from where your western disturbances are coming from Mediterranean Sea, right? It's coming from Mediterranean Sea. Where is Mediterranean Sea? In the west. Where? Between what? What is the latitude? 35, 35 degree. Okay. So, what will happen from here? There would be, it is known as what? Western disturbances, subtropical jet streams. When all the tropical jet streams come here, when do they come? When do they come down? In winter. In winters. But we are not talking about that. Right now, we are talking about only monsoons in summers. We are talking about summers right now. Okay. But Indian monsoon of western disturbances, which is the formation of southwest Indian monsoon, has a very big role in that too. So, we have to discuss it here. Right. We will do discuss it in a detail in few minutes. But, But abhi ke liye what you have to understand, the position of this subtropical jet stream is little low. Kab winters mein. Lekin jaisi hi summers approach hotay hain, what will happen? This will fade away, it will move towards north. It moves higher. Very good, excellent. It moves towards higher latitudes. Aur jab hi higher latitudes ki tarah chala jayega, what will happen? the tropical, eastern tropical jet stream even more gets gets strength alone right so because this is getting faded away this is also one of the reasons so if this comes in your option then yes this is correct write down subtropical jet streams write down the explanation s t j s t j moves to the north of Himalayas move to the north of Himalayas during summer. comma contributing to contributing to the formation contributing to the formation and strength of south west monsoon contributing to the strengthening of south formation and strengthening of southwest monsoon Next slide, very important one, intertropical convergence zone. Intertropical convergence zone, right now, ITCZ. ITCZ. the itc z is a broad trough of low pressure in equatorial latitudes in equatorial latitudes where north east and south east trade winds converge. Where north east and south east trade winds converge. It shifts. north or south. It shifts north or south with apparent movement of the sun influencing, influencing the monsoons onset, the monsoons onset and advance. monsoons onset and advance. What will happen here? See what is ICTZ? What is inter-tropical convergence zone? What is this? What is this inter-tropical convergence zone? Understand. See. Ideally what we do, this concept you have already done, we just need to go back to it to understand this. Ideally we take that the low pressure area is being created at the equator, which is your 0 degree. We ideally take it as a 0 degree, at which your doldrums are being created. This is the equator. But what happens, it is not necessarily. What is this? Latitude is what? Your imaginary line. Why? Because we want to make you understand certain phenomena. But it is not necessary that the phenomena that I experience at the zero degree happens at zero degree only. What will happen? Because the earth, because the sun is moving towards northern hemisphere. In northern hemisphere during summers, it can happen that the phenomena that is experienced at zero degree can be experienced above it. Can it happen like that? Can it happen? Are you understanding what I am trying to tell you? Online students, are you with me? the phenomena that is experienced at zero degree it might happen is not experienced here but rather here above it like zero degree pinna okay five degree phenomena right it can happen like that now it can happen so i will assume this as a what my region of low pressure because the features the characteristics which ideally this should have shown this is not showing this latitude is showing which is five degree north talking in northern hemisphere summer season this is showing right so i should say this is known as what here what will happen same phenomena my trade winds are coming and they are converging here trade winds are coming and converging here and this is from the southern hemisphere this is in the northern hemisphere right this is in southern this is in northern hemisphere so the convergence is taking place here so ideally this should have been the place but the same characteristic same phenomena not been present here they have just moved above the equator this is known as intertropical convergence zone. What we call it as intertropical convergence zone. In summers, it moves above in northern hemisphere and in winters, what will happen? It will move below zero degree, okay? It will move in the towards the south in winters, right? So what this statement is saying IT sees that it's a broad of low pressure in equatorial latitudes where the north east and south east trade winds converge. It shifts north or south with the apparent movement of sun. Who is responsible for this shifting? Sun. With the apparent, what is written? With the apparent movement of sun. And this is responsible for onset of monsoons. Please go through what I have made you write Abhi. So please ask your doubts if you have any. Write down about southwest monsoon. You have not written about southwest monsoon. Please write down southwest monsoon. Take two minutes and let me know if you have any doubt. I have written on, write down. India's climate is dominated by monsoons. next point monsoons are strong comma often violent often violent wins that change uh sanjana is asking man basically it's a five degree but it feels yes exactly right Often violent winds that change direction with the season. Write down next line. The term technically is the second point. The term technically describes seasonal reversal. seasonal reversals of wind direction caused by temperature differences caused by temperature differences between land and sea temperature differences between land and sea breeze. What do we call this as? Land and sea breeze difference. We call it as differential heating. We have done this already in the starting of climatology. Differential heating. Write down creating zones of comma, creating zones of high and low pressure creating zones of high and low pressure over land in different seasons. Right on next. Monsoons occur every year. See, intensity of monsoons can change. That we will understand. There's like La Lina, El Lino, right? We will understand that. But monsoons will come, right? We are going to study two phenomena, which is El Lino and La Lina, right? El Lino is what? It's giving a brief description. El Lino is you're bringing your drought years. this is less amount of rainfall will happen in India. Lalina is more intense rainfall will happen and it will be good for the agriculture, right? So this intensity can differ but you can't say that monsoons will not come. So they will occur. Now write down monsoons occur every year in many countries around the world. other than South Asia, North Australia, South Asia, North Australia, Africa, South America and other places along with this also gets affected. The southwest monsoon has warm winds blowing from Indian Ocean. full stop its span is its span is june to september its span is june to september comma with 75 percent of with 75 percent of annual rainfall in India with 75% of annual rainfall in India full stop. It varies from 10 centimeter in western Rajasthan to over 900 cm in Meghalaya. The mountains of southern india split the the mountains of so then which all mountains we have we have mountains here right the western gods here we have mountains right which mountain is present here your cardamom right then you're a naimudi so what will happen basically it's a one branch only when But what will happen? It will divide the branch also. Okay. So write down mountains of southern India split the summer winds. The western arm, which is the western arm? This one, your Arabian one. The western arm of the monsoon is deflected. is deflected northwards, is deflected northwards, by the Western Ghats, by the Western Ghats, to Mumbai and the other parts of India. The eastern arm of the southwest wind travels through Bay of Bengal, travels to Bay of Bengal, to Kolkata, Assam, Kolkata-Essam and other north eastern region of the country bringing heavy rainfall in the regions like bringing heavy rainfall in the regions like Meghalaya. Write down the next point. The Bay of Bengal Branch shifts towards India due to the presence of of due to the presence of upper circulatory atmospheric wind, upper circulatory atmospheric wind known as tropical easterly jet stream known as tropical easterly jet stream bracket me likhingi east to west it blows from east to west what have you written so far please repeat repeat it for me The top best mountain that orbits the rock Indian Ocean. No, no, the last point only. Only the last point. The Deva Pond which is towards India's eastern presence of a pan-circulatory bridge known as the Robidus Pisternation. Right. Now, write down. This movement of Bay of Bengal branch brings heavy rainfall in the interior part of India. But as it moves towards west, as it moves towards west, it loosens, it loosens its moisture, it loosens its moisture and hence it is unable. to, it is unable to bring rainfall in the regions like Rajasthan. It is unable to bring rainfall in the regions like Rajasthan. So Rajasthan is not getting from here. Why? Because it runs parallel. It's not striking. There's no mountain. Had there been a mountain, what will happen? they would have striked here. If there were mountains in Rajasthan, what would have happened? It would have obstructed the path of Arabian branch. Once obstructed the path of Arabian branch, they would have got a huge rainfall here. But it runs parallel, right? And the Bay of Bengal branch also, it loses some moisture. So that's why also it is not bringing the rainfall here. The best rainfall will happen where? In this region. Why? Because the moisture that they have just picked up, They will. bring a rainfall in this part okay right down that the position of tropical easterly jet stream the position of tropical easterly jet streams is not fixed it not fixed. It can vary due to various reasons and hence it can change the intensity of rainfall in various years. intensity of rainfall in various years right tied down the heaviest monsoon rainfalls the heaviest monsoon rainfalls occur where the winds blow side to side down like this tight hyphen on side on to the hills full stop the higher the hills and more moist the air. Higher the hills, more moist the air power and then greater the amount of rainfall. Next point. These factors give Chera Poonji. These factors give Cherrapunji in Meghalaya one of the highest rainfall. Now it has changed, right? This is not the place where you are having the highest. This is Mosingrom, right? But this is second highest. Okay. So, highest rainfall. One of the highest rainfall in the world. Full stop. Right. Alright. So, now what we have to do? We have to. understand another kind of monsoon that we have which is your retreating monsoon so now your knowledge of subtropical your subtropical jet streams or your Western disturbance knowledge will come in understanding retreating monsoons okay So in September, October what will happen? Now the sun is gradually shifting towards southern hemisphere, right? As you have seen experience it always that once September is there or October is there, evening ka time jo hota hai, the whole day gets get over or at around 6.30 or 6, right? So you start understanding the point that winters are approaching. How do you understand? Summer is 7.30, it's a full day. So you start understanding it through what sunrise and sunsets. At what time the sunset is happening. If it's happening at 6.15, 6.30 then you will start understanding the winters are approaching. So what will happen in September or October? the sun position starts shifting towards gradually towards south right understand understanding this point right so what will happen then you have done this in different seasons right we all have done that online students any doubt till here we have done different seasons right so what will happen and then the low pressure region which was being created here what will happen the low pressure region which has been created here it will start getting ferried away plus western disturbances which is coming from this region which region mediterranean sea this area your himalayas right drawing it like that because I want to show Himalayas here. They will come or they will come from this side and hit Himalayas. Because of Himalayas, it will have two branches. One branch will come inside the Indian continent or Indian region and one will move above. This is responsible for bringing rainfall and this is risk with the above one is responsible for bringing right right One has come here, inside India, right? And we will come here. What is this direction known as? This direction is known as North East. Can you identify the direction, all of you? This is North East, right? This is the direction. So, once it will come here, it will pick up the moisture from Bay of Bengal and there will be a heavy rainfall happening here in Tamil Nadu region. How many of you know that southwest monsoon winds are not able to bring rainfall in Tamil Ladu region. Rainfall which is happening in Tamil Nadu region is because of this retreating mountains, which is this north east winds. Why north east? Because of the direction. Right. How many of you can get this? First, I'll explain it again. Write down. Retreating monsoon slash northeast monsoons. Write down the heading. Retreating monsoon slash northeast monsoons. Write down. Retreating monsoons in India. Retreating monsoons in India refers to withdrawal of. Retreating monsoon in India refers to. The withdrawal, withdrawal means paid away, right? Nikal li na, withdrawal of money, right? Retreating monsoon in India refers to the withdrawal of the southwest monsoon, PAMA, typically occurring from September to December. Full stop. As the monsoon winds start retreating, as the monsoon winds start retreating, they shift from south-west to south-east due to two reasons. coming from northeast, right? But where they will hit here? This position is not known as southeast, right? Okay, due to two reasons. First, decreasing temperature in north India. First, decreasing temperature in North India and second shifting of the Sun shifting of the Sun southwards yes Sanjana I will first write shifting of the Sun in sorry shifting of the Sun southward right on the next The south eastern coast, this one, the south eastern coast, that's why what happens, if you see the aircraft or if you're just booking the flight for Chennai in November, December, what will happen? The cancellation of flights or even what happens? The prices are very, very high, soaring prices. Reason being, because at that point of time, even if you have seen a very famous movie, which. Having what? What is in November, December? There is a lot of rainfall here. Right? So what will happen here? What will happen here? The warning system gets alert. Your disaster management, everything gets activated. Reason being? Because here the kind of rainfall it brings in, in November, December is quite high. Right? It's quite high. and reason being this Tamil Nadu area and the volunteers and the disaster management authorities they have to take care they are quite vigilant in these times and you see the warnings also the pilots and everybody they are not allowed to freely move here they have to check lot of things that if the storm comes then what will happen they won't be able to land it nicely Next point, the southeastern coast, particularly Tamil Nadu, receives heaviest rainfall, receives heaviest rainfall, full stop. This is because, this is because, during retreating monsoons, this is because, during retreating monsoons, the north east monsoon winds picks up the moisture from Bay of Bengal, picks up the moisture from Bay of Bengal and bring it to Tamil Nadu and bringing to Tamil Nadu, Burma causing rainfall in this region, causing rainfall, bringing heavy rainfall in this region. Right? Please draw the diagram. I done one more point. Much of the India experiences, much of the India experiences feeble, feeble and infrequent. Feeble means weak. Infrequent precipitation, infrequent precipitation during retreating monsoons. okay the winds are what this winds which are coming from the north seas they are going to be what kind of winds they are dry winds they are dry winds reason because there is no moisture present on the land after southwest winds what were they they were moisture laden winds this is moisture lead and moisture ladder means they carry the moisture why because they are picking up the moisture from here and going there and bringing right but it's coming all from Indian Ocean only but here as it will move here it will loosen up its moisture and this is what ideally it is offshore or offshore winds are mostly what they are dry winds this is what onshore your southwest winds are onshore so your offshore wind is a dry wind. written right down this is responsible for bringing dry winds in India as it is an offshore wind. Right. Next. So I'll be explaining the whole process again. Sanjana, anybody has any other doubt? Yes, I'm doing that. No problem. OK. This is, have you done that lecture of subtropical or westerly jet streams, the western disturbances? If you haven't done it, then please go back to that. chapter again that lecture again so that you can understand it in a better way right so these this is what this is coming from west these are your jet stream which extreme particularly your subtropical westerly jet streams or you call it as western disturbances now since it's coming from there what will happen this is coming in which year which month around september september to December. These winds are going to be present on India. As soon as the monsoon comes in the summer time, this moves northwards. It is present only between September to December. So these are Himalayas. It is striking here at the mountains and there's going to be two branches of this. one branch which is coming here this is responsible for bringing rainfall and in the later times what will happen it will this will bring flow now it will go till where your northeast now due to syntaxial bend this is a textual bend present where in present in northeast right this is syntaxial bend. This is because of the geomorphology chapter. In the geomorphology, you would have studied this, right? Because of this syntaxial bend, what will happen? It is bound to move like this, right? When it will move like this, it's going to pick up the moisture in Bay of Bengal and it will bring a heavy rainfall in this region, which we call it as Tamil Nadu. These winds are further going to go inside the Indian subcontinent in the interior of the India right and this will bring these are going to be your dry winds and also you call it as offshore okay these are known as your retreating monses then sanjana clear okay these are your upper circulatory these are not a surface winds please i told you these are not your surface your easterly trade winds your westerly trade winds your westerlies your easterly sorry your westerly trade uh wins yeah yeah you can okay your easterlies your westerlies they are what they are your surface wins but if i talk about this these are your upper circulatory wins right any doubt online students turaj archal harshika rakshat sanjana everyone please i cannot take everybody's name because list is going to be too long right the next part we are going to do what your indian ocean dipole which is also important phenomena right it is also affecting a monsoon then your ellino your lalino you must have heard about it i have also had a discussion about it very brief discussion but it's going you have to do it in detail right your monsoons are incomplete without it okay online students any doubt you're having any doubt okay also please do not forget to go to your PYQ, you go to PYQ today and try to practice this, especially this monsoons. Okay, you will see that if you, there would be certain options which might be very very tricky. So, what you have to do is mark those questions and bring them tomorrow so that we can have a detailed discussion. What will happen with that? The confusion that you must be having a bit. Whatever is there, by doing PYQ it will all go away. When you will have detailed discussion tomorrow then that and also practice means PYQ. One PYQ or else just write down simply what are retreating monsoons sigma please write down on your own with the diagram. So it will give you the clarity. Clarity aise hi melegi by frequent revisions. Alright. Thank you so much girls. Thank you all the YouTube viewers. Thank you and online students please do this assignment. Yes, this is completed only, Rakshath. But there is one more thing which is important and we have to do it tomorrow. Alright, thank you.

All right. Welcome all to Plutus IS. And today, we are going to start with Indian monsoon. All right.

In the previous live session in which we have met, we have discussed about different issues. I don't like it. Okay, I will try it.

Should I start or not? You can start by looking at the comments. I will have to open the comments on that, right?

Yes. Welcome all to Prutus IS. Today we are going to discuss about Indian Monsoon. In the previous lecture, live lecture that we have done, we have engaged so many people and thank you so much that so many people, viewers were there at that time.

But what I thought at that time, apart from the online students which are already present in the class, the viewers who are watching on the YouTube, they should interact much more because I'm constantly watching the, I'm constantly reading the comments. that this is a live session that you're going you're watching and if you want to interact in mid or middle of the session then you can definitely do that i'll be responding to each one of you as much as it is possible right so indian monsoon is very very important from the prelims and the mains perspective and before starting this okay so before starting this i will also like to give some of the fundamentals of the geography which are required to understand the Indian monsoon because I want to keep this session so that everyone, everyone who has even not done anything related to the winds or the seasonal winds or anything related to high pressure, low pressure and people who have already done anything related to climatology that's excellent but people who are not come from that background maybe they have not covered that in their syllabus. they can also understand right all right online students uh very good evening right keep on interacting with me okay right so indian monsoon why it is important i told you because majorly how many questions comes in means at least two questions are expended expected or one question is expected out of it right and in freelance you expect a question definitely a question from it now conceptually you are required to be sound in this reason being lot of times UPSC throws a conceptual question at you which you might not be able to solve if you have not done the concept very very clearly okay first draw the diagram okay i hope that everybody knows how to draw indian map if you don't know you will just get a practice of it with consistent drawing okay because of the lack of space i'm not drawing so i have to show a area below the equator okay all right in june or you can precisely say may and june right the sun is overhead or sun is Giving the maximum insulation where in northern hemisphere How has the maximum insulation there ahead northern hemisphere?

Right it is giving maximum insulation in northern hemisphere Why as you know the northern hemisphere what happens in May June, right? What is starting coming in your summers right as summers are approaching what will happen? the Sun will move to it will move to northern hemisphere, right? Once it moves to northern hemisphere, there would be what? There would be direct insulation.

That means the area above the equator, which is northern hemisphere, will be more heated up as compared to the southern hemisphere, right? Anything, any doubt regarding this till here? Any doubt?

So, what this phenomena is known is I hope that you all have done the different seasons, right? you have done different seasons how many seasons we have summer winter and we have equinox right spring and autumn right so all these seasons that we have in particularly i am talking about the summers where the sun is moving above the equator and it is giving more constant sunlight insulation is being there in the northern hemisphere so what will happen this will become a region of low pressure this will become a region of low pressure and in southern hemisphere it will become a region of high pressure okay what is low pressure relatively high relatively low right because here the insulation is not going to be much more so what will happen in that as i have told you earlier also and for the people who are just going to this topic for the first time please like don't Wind always blow from wind always blow from high pressure to low pressure This is a universal rule that you have to remember that it always blow from high pressure to low pressure Which means we are talking about surface winds. This is the surface wind that I'll be talking about It is it is moving from high pressure to low pressure.

Please write down make a note and write down in your notebooks. Winds always blow from high pressure to low pressure. So once the winds are blowing from high pressure to low pressure, this is known. This is coming from southern hemisphere.

This is coming from southern hemisphere. Once it crosses, I'm taking a different color pen. Once it crosses the equator, what will happen?

Do you think the wind direction is going to be like this as I have shown it to you? Okay, for the people who cannot see the board clearly, I'm drawing it here. So consider this as the Indian map. This is equator. Okay, the wind is coming from this side, right?

I've shown the wind direction of the winds like this. Do you think the wind direction is going to be like this straight? No.

Reason B? Tell me the reason. Online students, what is the reason?

Because I have told you that there is a constant force which is working on the wind which is known as Coriolis. Coriolis force, right? Since the Coriolis force is working, what will happen? It will change its direction, right?

It will change its direction. So, once it moves towards the equator, what will happen? In the northern hemisphere, the Coriolis force, where it gets deflected?

Coriolis force? moves towards right. It deflects towards right.

Where? In northern hemisphere. For example, this is the direction of the wind in the northern hemisphere.

How it will be deflected? Right or left? It will be deflected?

Right. Right. In the northern hemisphere, please write down northern hemisphere, the wind is going to get deflected towards right.

Towards right. And in southern hemisphere in southern hemisphere due to Coriolis force due to Coriolis force wind is going to get deflected towards left right okay so since the wind is coming from here right Now it is going to deflect in this direction. Can you tell me the direction of this wind?

Can you tell me the direction of this wind? What is this direction? Yes, Sanjana, you are right.

What is the direction of this wind? No, what is this direction called? What is this direction called?

It is southwest. It is south. So, can I call it as a south west winds, right? Can I say that the south west winds are coming from the and they are hitting where Indian subcontinent, right? They are coming and hitting Indian subcontinent.

Now, once this wind comes, what will happen? There would be two branches of this wind. Your southwest wind will have how many branches? Two branches. It will have two branches.

One is Arabian branch and another one is your Bay of Bengal. branch, Bree of Bengal branch. Okay, so when you talk about that monsoon are approaching, hum kya baat karte hain ki jab monsoon aa raha toh sabse pehle kaha pe hit hota hai? When we have seen news channels right in May or in June, you talk about that arrival of monsoon right.

So we talk about where it is hitting first, so where it is expected that the monsoon will come. It is in Kerala. The first monsoon comes in Kerala.

Then your Karnataka and other region. Then Mumbai. Right.

And then Mumbai means Maharashtra. Right. So it will come in different states. So but first it comes where?

In Kerala. If we talk about this coastline, I'm talking about particularly this area of India, it will come to Kerala state. Right.

what will happen next? What will happen next? Right? So what will happen? Then it will move parallel, this will move parallel and this will move towards your north system area.

What is your north system area known as? Your how many states? Your Meghalaya, Manipur, Tirupura, Arunachal Pradesh, Assam, right?

So it will move and it will hit this area. Once it hits this area, there will be a rainfall in northeastern. Why?

Because of Bay of Bengal branch, right? But Arabian branch goes parallel with this area. What is this area known as? Rajasthan.

It goes parallel to the Rajasthan. So please understand this concept. if the winds are not going to... get what?

They are not going to get hit, right? You need to hit a place, right? In order to get a rainfall, but it is just running parallel. It is running parallel to this area. So what will happen?

There will be no rainfall here. We are in Rajasthan. There are other reasons also why Rajasthan is not having a rainfall. But one of the reasons why I mean not having a rainfall means less amount of rainfall.

It is experiencing minimum amount of rainfall. in an annual year. So why it is happening? It is happening because one of the reason is this and another reason I will discuss with you after few minutes. So this is one of the reason why Rajasthan is not experiencing rainfall because of the Arabian branch.

Reason being it runs parallel where towards the near this area okay any doubt in this please have a look at all the concepts and let me know if you have any doubt Yes, people who are watching online, I mean the viewers on YouTube can also interact in between of this lecture. I'll be constantly reading your comments. Okay, online students, is it clear to you? Please raise your hands or use the chat box. Alright, done.

I'll make you write everything, don't worry. Okay, next. So this is again, I'm drawing this area.

There will be rainfall in north eastern region, right? Now, This Bay of Bengal branch moves towards interior of the earth, interior of the Indian subcontinent, right? It moves towards the interior of the subcontinent.

It moves, it deflects towards interior of the Indian subcontinent. subcontinent. Can you tell me the reason why? Can you tell me the reason we have done that?

We have already done that. We have discussed about that jet stream. I'm giving you the hint. Yes.

can you tell me this is the one of the branch right it is going towards this this is bay of bengal this is Now tell me, ideally what should have happened? This branch should have gone and it should have crossed the Arakan mountains range and then it would have gone to other Southeast Asian here, different countries, right? Myanmar, right? But it does go there also, but why it is deflecting back inside of the Indian subcontinent?

What is the reason behind that? because of the trade means maybe. Sanjana, trade means are not responsible for it.

I gave you the hint that I'm discussing. The hint that I gave to you is a jet stream and many times while I was going through that lecture, I have discussed that this jet stream is having a huge role in Indian monsoon. It is because of the tropical easterly jet streams which move from east to west has a huge role in deflecting the winds inside the Indian subcontinent.

What will happen? See, this wind ideally should have gone like that right but because of this jet streams because of tropical easterly jet streams, the winds are coming inside and this is majorly responsible for bringing the rainfall in the states which are in the interior part of the Indian subcontinent. What they are doing?

They are picking up the moisture from the Bay of Bengal, what sea? They are picking up the moisture from here and once they pick up the moisture from here, they will bring rainfall in the north eastern area and then half of that will come inside. Why? Because of the tropical easterly jet streams.

Once they come inside, what they do? They bring... huge heavy rainfall right and as they move they keep on moving right as they move what will happen this branch this bay of bengal winds what they will do their bay of bengal branch this will loosen the moisture It is responsible for the rainfall. It will just responsible for the rainfall when there will be moisture present in it.

Agar wind mein moisture nahin hoga because they are coming on the land. Now they are not having enough what? Moisture present as they are moving inside.

So their moisture would be not enough to bring rainfall in which part? In the Rajasthan area. Right?

How many of you can understand? than this concept or if you have any doubt please ask take two minutes just go through it and ask Write down. Just start the Indian monsoon.

Write down the heading Indian monsoons. Yes, Rakshath, Achul, Harshika, Sanjana, Ruhans, Suraj. Please ask if you have any doubt. It's amazing ma'am because I can't take the life.

I have watched all the recorded lectures. Good Sanjana. No problem.

Yes, sometimes in between we are conducting the live lectures of the ongoing batches. right? So then you can watch from there, okay?

Write down, monsoons are seasonal winds, monsoons are seasonal winds which reverse their direction, which reverse their direction, monsoons are seasonal winds which reverse their direction. with the change of season. Write down, full stop.

The monsoon is a double system of... Please let me know if my speed is too fast. Write down. Write down. The monsoon is a double system of seasonal winds.

Monsoon is a double system of seasonal winds. which, then write down, they flow from sea to land during summer. They flow from sea to land during summer and from land to sea during winter. Write down. They flow from sea to land during summer.

Have you not seen the diagram? What do we call this as? When there is winds coming from sea to land, we call that as... onshore.

This is known as onshore winds and when they are from land to sea, this is known as offshore. Always remember, right? Offshore is land to sea.

Full stop. India receives southwest monsoon winds. India receives Southwest monsoon winds in summer. Monsoon winds in summer. and north east monsoon winds in winter.

Please underline both. Please underline south west monsoon winds in summer and north east monsoon winds in winter. Now write down factors responsible sectors responsible for southwest factors responsible for southwest monsoons right on the first point intense heating of tibetan plateau intense heating of tibetan plateau Please understand this point carefully. See, where is tibbath? Here.

This tibbath is an elevated area or elevated plateau. This is an elevated plateau. Elevated means, thoda uthava. So it's an elevative. It is rising above sea level.

The height between the sea and the land is quite flat. Kitna? Flat to jitna. So in summers, or you can say in the month of May, what will happen?

It will get too much of insulation. And it will create a region of low pressure. It will create a region of low pressure. Right?

So that's why this is also one of the major factor why it is attracting what? Southwest winds. Why it is attracting southwest winds?

Why? Because this is an area of high pressure. And this has become an area of low pressure.

When this has become the area of low pressure, it will attract. winds towards it. Intense heating of tibetan plateau.

Tibet is an area which is elevated. and in summers and in summers, the tibetan plateau gets the tibetan plateau gets intensely heated. Thus forming the region of low pressure thus forming the region of low pressure leading to strong vertical air currents Right on the next.

Tropical easterly jet. Tropical easterly jet. write down in the short form you can write tej also also known as african easterly jet also known as african easterly jet comma set in along 15 degree north latitude of the withdrawal of westerly jet streams.

Westerly jet streams. What do you mean by that? See, your tropical easterly jet stream, this one, I have given you 15 degree knot.

But do you think it is fixed? It is not fixed. Because tropical easterly jet streams, the position of that can also vary. For example, this year the tropical easterly jet has come just above the Odisha, right?

But it can also come like this. So, what will happen? Because tropical easterly jet is coming here, so it will bring what?

More rainfall in the southern India as compared to central and northern India, right? Once it is lower in the position, right? It can also happen that this in the same area it can come right but i cannot fix the latitude like that on an average i have given a latitude to you that is 15 degree dot but it can be more in the southern area then it will be responsible for bringing heavy rainfall in the this area right or it can also move a little upwards right depending upon different factors the position of the tropical easterly jet streams can change right so write down taj also known as african easterly jet comma sets in along 15 degree north latitude after withdrawal of westerly jet stream written till here right first off this jet streams helps in the This jet stream helps in the burst of the monsoon.

This jet stream helps in the burst of the monsoon in India. It leads to burst of the monsoon in India. As it helps in strengthening the...

as it helps in strengthening the south west winds. Next write down permanent high pressure cell. These points are extremely extremely important for the prelims because in prelims they will ask there's a question will be given that which all factors are responsible for southwest monsoons. Then four options will be given to you and if four options will be given to you then you have to select one.

If you will not have the a conceptual knowledge then there is a big chance high chance that you might pick against wrong option right now write down permanent high pressure cell in the South Indian Ocean. In the South Indian Ocean. Yes, Rakshata, I'll address your query just after dictation.

Okay, write down. A permanent high pressure cell exists east of Madagascar, east of Madagascar. Where is Madagascar?

Africa, right? This is What? Madagascar. Right?

This is Madagascar. Okay? Below your equator.

So in which region basically it is? southern hemisphere. I told you because the sun is over northern hemisphere.

So, it will experience what? High pressure. It's a high pressure zone.

So, what my statement is saying that east of Madagascar what will happen? there will be what permanent high pressure zone what you have written so far what do you have written so far okay comma approximately at 20 degrees south over the indian ocean over the Indian Ocean. full stop the intensity and the intensity and position of the high pressure area the intensity and the intensity and position of the high pressure area significantly affect the Indian monsoon. Significantly affect the Indian monsoon. Next write down subtropical jet streams.

Subtropical jet streams. How many of you remember the subtropical jet streams? We have just covered the topic. recently subtropical geltring.

These are also known as with western disturbances. These are also known as what? Western disturbances and since they are known as western disturbances, what will happen? They are responsible for they are also responsible they also contribute in Indian monsoon making differently we'll come to that okay they have a huge role in Indian monsoon as well but we'll come to that Abhi Kili please understand this so this wins all right I'll explain here only see from where your western disturbances are coming from Mediterranean Sea, right? It's coming from Mediterranean Sea.

Where is Mediterranean Sea? In the west. Where?

Between what? What is the latitude? 35, 35 degree. Okay.

So, what will happen from here? There would be, it is known as what? Western disturbances, subtropical jet streams. When all the tropical jet streams come here, when do they come? When do they come down?

In winter. In winters. But we are not talking about that. Right now, we are talking about only monsoons in summers.

We are talking about summers right now. Okay. But Indian monsoon of western disturbances, which is the formation of southwest Indian monsoon, has a very big role in that too. So, we have to discuss it here. Right.

We will do discuss it in a detail in few minutes. But, But abhi ke liye what you have to understand, the position of this subtropical jet stream is little low. Kab winters mein. Lekin jaisi hi summers approach hotay hain, what will happen?

This will fade away, it will move towards north. It moves higher. Very good, excellent.

It moves towards higher latitudes. Aur jab hi higher latitudes ki tarah chala jayega, what will happen? the tropical, eastern tropical jet stream even more gets gets strength alone right so because this is getting faded away this is also one of the reasons so if this comes in your option then yes this is correct write down subtropical jet streams write down the explanation s t j s t j moves to the north of Himalayas move to the north of Himalayas during summer.

comma contributing to contributing to the formation contributing to the formation and strength of south west monsoon contributing to the strengthening of south formation and strengthening of southwest monsoon Next slide, very important one, intertropical convergence zone. Intertropical convergence zone, right now, ITCZ. ITCZ.

the itc z is a broad trough of low pressure in equatorial latitudes in equatorial latitudes where north east and south east trade winds converge. Where north east and south east trade winds converge. It shifts. north or south. It shifts north or south with apparent movement of the sun influencing, influencing the monsoons onset, the monsoons onset and advance.

monsoons onset and advance. What will happen here? See what is ICTZ? What is inter-tropical convergence zone? What is this?

What is this inter-tropical convergence zone? Understand. See. Ideally what we do, this concept you have already done, we just need to go back to it to understand this.

Ideally we take that the low pressure area is being created at the equator, which is your 0 degree. We ideally take it as a 0 degree, at which your doldrums are being created. This is the equator.

But what happens, it is not necessarily. What is this? Latitude is what?

Your imaginary line. Why? Because we want to make you understand certain phenomena.

But it is not necessary that the phenomena that I experience at the zero degree happens at zero degree only. What will happen? Because the earth, because the sun is moving towards northern hemisphere.

In northern hemisphere during summers, it can happen that the phenomena that is experienced at zero degree can be experienced above it. Can it happen like that? Can it happen? Are you understanding what I am trying to tell you?

Online students, are you with me? the phenomena that is experienced at zero degree it might happen is not experienced here but rather here above it like zero degree pinna okay five degree phenomena right it can happen like that now it can happen so i will assume this as a what my region of low pressure because the features the characteristics which ideally this should have shown this is not showing this latitude is showing which is five degree north talking in northern hemisphere summer season this is showing right so i should say this is known as what here what will happen same phenomena my trade winds are coming and they are converging here trade winds are coming and converging here and this is from the southern hemisphere this is in the northern hemisphere right this is in southern this is in northern hemisphere so the convergence is taking place here so ideally this should have been the place but the same characteristic same phenomena not been present here they have just moved above the equator this is known as intertropical convergence zone. What we call it as intertropical convergence zone.

In summers, it moves above in northern hemisphere and in winters, what will happen? It will move below zero degree, okay? It will move in the towards the south in winters, right? So what this statement is saying IT sees that it's a broad of low pressure in equatorial latitudes where the north east and south east trade winds converge. It shifts north or south with the apparent movement of sun.

Who is responsible for this shifting? Sun. With the apparent, what is written? With the apparent movement of sun.

And this is responsible for onset of monsoons. Please go through what I have made you write Abhi. So please ask your doubts if you have any.

Write down about southwest monsoon. You have not written about southwest monsoon. Please write down southwest monsoon.

Take two minutes and let me know if you have any doubt. I have written on, write down. India's climate is dominated by monsoons.

next point monsoons are strong comma often violent often violent wins that change uh sanjana is asking man basically it's a five degree but it feels yes exactly right Often violent winds that change direction with the season. Write down next line. The term technically is the second point.

The term technically describes seasonal reversal. seasonal reversals of wind direction caused by temperature differences caused by temperature differences between land and sea temperature differences between land and sea breeze. What do we call this as? Land and sea breeze difference.

We call it as differential heating. We have done this already in the starting of climatology. Differential heating.

Write down creating zones of comma, creating zones of high and low pressure creating zones of high and low pressure over land in different seasons. Right on next. Monsoons occur every year. See, intensity of monsoons can change.

That we will understand. There's like La Lina, El Lino, right? We will understand that. But monsoons will come, right? We are going to study two phenomena, which is El Lino and La Lina, right?

El Lino is what? It's giving a brief description. El Lino is you're bringing your drought years. this is less amount of rainfall will happen in India. Lalina is more intense rainfall will happen and it will be good for the agriculture, right?

So this intensity can differ but you can't say that monsoons will not come. So they will occur. Now write down monsoons occur every year in many countries around the world. other than South Asia, North Australia, South Asia, North Australia, Africa, South America and other places along with this also gets affected. The southwest monsoon has warm winds blowing from Indian Ocean.

full stop its span is its span is june to september its span is june to september comma with 75 percent of with 75 percent of annual rainfall in India with 75% of annual rainfall in India full stop. It varies from 10 centimeter in western Rajasthan to over 900 cm in Meghalaya. The mountains of southern india split the the mountains of so then which all mountains we have we have mountains here right the western gods here we have mountains right which mountain is present here your cardamom right then you're a naimudi so what will happen basically it's a one branch only when But what will happen? It will divide the branch also. Okay.

So write down mountains of southern India split the summer winds. The western arm, which is the western arm? This one, your Arabian one. The western arm of the monsoon is deflected.

is deflected northwards, is deflected northwards, by the Western Ghats, by the Western Ghats, to Mumbai and the other parts of India. The eastern arm of the southwest wind travels through Bay of Bengal, travels to Bay of Bengal, to Kolkata, Assam, Kolkata-Essam and other north eastern region of the country bringing heavy rainfall in the regions like bringing heavy rainfall in the regions like Meghalaya. Write down the next point. The Bay of Bengal Branch shifts towards India due to the presence of of due to the presence of upper circulatory atmospheric wind, upper circulatory atmospheric wind known as tropical easterly jet stream known as tropical easterly jet stream bracket me likhingi east to west it blows from east to west what have you written so far please repeat repeat it for me The top best mountain that orbits the rock Indian Ocean.

No, no, the last point only. Only the last point. The Deva Pond which is towards India's eastern presence of a pan-circulatory bridge known as the Robidus Pisternation. Right.

Now, write down. This movement of Bay of Bengal branch brings heavy rainfall in the interior part of India. But as it moves towards west, as it moves towards west, it loosens, it loosens its moisture, it loosens its moisture and hence it is unable.

to, it is unable to bring rainfall in the regions like Rajasthan. It is unable to bring rainfall in the regions like Rajasthan. So Rajasthan is not getting from here.

Why? Because it runs parallel. It's not striking. There's no mountain.

Had there been a mountain, what will happen? they would have striked here. If there were mountains in Rajasthan, what would have happened?

It would have obstructed the path of Arabian branch. Once obstructed the path of Arabian branch, they would have got a huge rainfall here. But it runs parallel, right? And the Bay of Bengal branch also, it loses some moisture. So that's why also it is not bringing the rainfall here.

The best rainfall will happen where? In this region. Why? Because the moisture that they have just picked up, They will. bring a rainfall in this part okay right down that the position of tropical easterly jet stream the position of tropical easterly jet streams is not fixed it not fixed.

It can vary due to various reasons and hence it can change the intensity of rainfall in various years. intensity of rainfall in various years right tied down the heaviest monsoon rainfalls the heaviest monsoon rainfalls occur where the winds blow side to side down like this tight hyphen on side on to the hills full stop the higher the hills and more moist the air. Higher the hills, more moist the air power and then greater the amount of rainfall. Next point.

These factors give Chera Poonji. These factors give Cherrapunji in Meghalaya one of the highest rainfall. Now it has changed, right? This is not the place where you are having the highest.

This is Mosingrom, right? But this is second highest. Okay.

So, highest rainfall. One of the highest rainfall in the world. Full stop.

Right. Alright. So, now what we have to do? We have to.

understand another kind of monsoon that we have which is your retreating monsoon so now your knowledge of subtropical your subtropical jet streams or your Western disturbance knowledge will come in understanding retreating monsoons okay So in September, October what will happen? Now the sun is gradually shifting towards southern hemisphere, right? As you have seen experience it always that once September is there or October is there, evening ka time jo hota hai, the whole day gets get over or at around 6.30 or 6, right?

So you start understanding the point that winters are approaching. How do you understand? Summer is 7.30, it's a full day. So you start understanding it through what sunrise and sunsets.

At what time the sunset is happening. If it's happening at 6.15, 6.30 then you will start understanding the winters are approaching. So what will happen in September or October?

the sun position starts shifting towards gradually towards south right understand understanding this point right so what will happen then you have done this in different seasons right we all have done that online students any doubt till here we have done different seasons right so what will happen and then the low pressure region which was being created here what will happen the low pressure region which has been created here it will start getting ferried away plus western disturbances which is coming from this region which region mediterranean sea this area your himalayas right drawing it like that because I want to show Himalayas here. They will come or they will come from this side and hit Himalayas. Because of Himalayas, it will have two branches.

One branch will come inside the Indian continent or Indian region and one will move above. This is responsible for bringing rainfall and this is risk with the above one is responsible for bringing right right One has come here, inside India, right? And we will come here.

What is this direction known as? This direction is known as North East. Can you identify the direction, all of you?

This is North East, right? This is the direction. So, once it will come here, it will pick up the moisture from Bay of Bengal and there will be a heavy rainfall happening here in Tamil Nadu region. How many of you know that southwest monsoon winds are not able to bring rainfall in Tamil Ladu region.

Rainfall which is happening in Tamil Nadu region is because of this retreating mountains, which is this north east winds. Why north east? Because of the direction.

Right. How many of you can get this? First, I'll explain it again. Write down. Retreating monsoon slash northeast monsoons.

Write down the heading. Retreating monsoon slash northeast monsoons. Write down. Retreating monsoons in India. Retreating monsoons in India refers to withdrawal of.

Retreating monsoon in India refers to. The withdrawal, withdrawal means paid away, right? Nikal li na, withdrawal of money, right?

Retreating monsoon in India refers to the withdrawal of the southwest monsoon, PAMA, typically occurring from September to December. Full stop. As the monsoon winds start retreating, as the monsoon winds start retreating, they shift from south-west to south-east due to two reasons.

coming from northeast, right? But where they will hit here? This position is not known as southeast, right?

Okay, due to two reasons. First, decreasing temperature in north India. First, decreasing temperature in North India and second shifting of the Sun shifting of the Sun southwards yes Sanjana I will first write shifting of the Sun in sorry shifting of the Sun southward right on the next The south eastern coast, this one, the south eastern coast, that's why what happens, if you see the aircraft or if you're just booking the flight for Chennai in November, December, what will happen?

The cancellation of flights or even what happens? The prices are very, very high, soaring prices. Reason being, because at that point of time, even if you have seen a very famous movie, which.

Having what? What is in November, December? There is a lot of rainfall here.

Right? So what will happen here? What will happen here? The warning system gets alert.

Your disaster management, everything gets activated. Reason being? Because here the kind of rainfall it brings in, in November, December is quite high.

Right? It's quite high. and reason being this Tamil Nadu area and the volunteers and the disaster management authorities they have to take care they are quite vigilant in these times and you see the warnings also the pilots and everybody they are not allowed to freely move here they have to check lot of things that if the storm comes then what will happen they won't be able to land it nicely Next point, the southeastern coast, particularly Tamil Nadu, receives heaviest rainfall, receives heaviest rainfall, full stop.

This is because, this is because, during retreating monsoons, this is because, during retreating monsoons, the north east monsoon winds picks up the moisture from Bay of Bengal, picks up the moisture from Bay of Bengal and bring it to Tamil Nadu and bringing to Tamil Nadu, Burma causing rainfall in this region, causing rainfall, bringing heavy rainfall in this region. Right? Please draw the diagram. I done one more point.

Much of the India experiences, much of the India experiences feeble, feeble and infrequent. Feeble means weak. Infrequent precipitation, infrequent precipitation during retreating monsoons. okay the winds are what this winds which are coming from the north seas they are going to be what kind of winds they are dry winds they are dry winds reason because there is no moisture present on the land after southwest winds what were they they were moisture laden winds this is moisture lead and moisture ladder means they carry the moisture why because they are picking up the moisture from here and going there and bringing right but it's coming all from Indian Ocean only but here as it will move here it will loosen up its moisture and this is what ideally it is offshore or offshore winds are mostly what they are dry winds this is what onshore your southwest winds are onshore so your offshore wind is a dry wind.

written right down this is responsible for bringing dry winds in India as it is an offshore wind. Right. Next.

So I'll be explaining the whole process again. Sanjana, anybody has any other doubt? Yes, I'm doing that. No problem. OK.

This is, have you done that lecture of subtropical or westerly jet streams, the western disturbances? If you haven't done it, then please go back to that. chapter again that lecture again so that you can understand it in a better way right so these this is what this is coming from west these are your jet stream which extreme particularly your subtropical westerly jet streams or you call it as western disturbances now since it's coming from there what will happen this is coming in which year which month around september september to December. These winds are going to be present on India. As soon as the monsoon comes in the summer time, this moves northwards.

It is present only between September to December. So these are Himalayas. It is striking here at the mountains and there's going to be two branches of this. one branch which is coming here this is responsible for bringing rainfall and in the later times what will happen it will this will bring flow now it will go till where your northeast now due to syntaxial bend this is a textual bend present where in present in northeast right this is syntaxial bend. This is because of the geomorphology chapter.

In the geomorphology, you would have studied this, right? Because of this syntaxial bend, what will happen? It is bound to move like this, right? When it will move like this, it's going to pick up the moisture in Bay of Bengal and it will bring a heavy rainfall in this region, which we call it as Tamil Nadu.

These winds are further going to go inside the Indian subcontinent in the interior of the India right and this will bring these are going to be your dry winds and also you call it as offshore okay these are known as your retreating monses then sanjana clear okay these are your upper circulatory these are not a surface winds please i told you these are not your surface your easterly trade winds your westerly trade winds your westerlies your easterly sorry your westerly trade uh wins yeah yeah you can okay your easterlies your westerlies they are what they are your surface wins but if i talk about this these are your upper circulatory wins right any doubt online students turaj archal harshika rakshat sanjana everyone please i cannot take everybody's name because list is going to be too long right the next part we are going to do what your indian ocean dipole which is also important phenomena right it is also affecting a monsoon then your ellino your lalino you must have heard about it i have also had a discussion about it very brief discussion but it's going you have to do it in detail right your monsoons are incomplete without it okay online students any doubt you're having any doubt okay also please do not forget to go to your PYQ, you go to PYQ today and try to practice this, especially this monsoons. Okay, you will see that if you, there would be certain options which might be very very tricky. So, what you have to do is mark those questions and bring them tomorrow so that we can have a detailed discussion.

What will happen with that? The confusion that you must be having a bit. Whatever is there, by doing PYQ it will all go away.

When you will have detailed discussion tomorrow then that and also practice means PYQ. One PYQ or else just write down simply what are retreating monsoons sigma please write down on your own with the diagram. So it will give you the clarity.

Clarity aise hi melegi by frequent revisions. Alright. Thank you so much girls.

Thank you all the YouTube viewers. Thank you and online students please do this assignment. Yes, this is completed only, Rakshath.

But there is one more thing which is important and we have to do it tomorrow. Alright, thank you.

Transcript for:Indian Monsoon System Overview

Transcript for:
Indian Monsoon System Overview