Monsoon in India Overview
The Arabic term for season, “mawsim,” is considered to be the source of the word “monsoon.” In essence, monsoons are seasonal winds that change direction as the seasons change. Thus, they are cyclical winds. The monsoons are a twofold system of seasonal winds that move from the sea to the land in the summer and from the land to the sea in the winter. The monsoons have always played a significant role because traders and mariners have relied on them to go. Despite the fact that monsoon occurs across the Indian subcontinent, central-western Africa, Southeast Asia, and a few other locations, the winds are strongest there.
India has northeast monsoon winds in the winter and southwest monsoon winds in the summer. The former occur as a result of the development of an intense low-pressure system over the Tibetan Plateau. The latter results from high-pressure cells that form across the Tibetan and Siberian plateaus.
Most of India experiences significant rainfall brought on by the south-west monsoon whereas the north-east monsoon primarily affects the south-eastern coast (Southern coast of Seemandhra and the coast of Tamil Nadu.). The majority of the annual rainfall falls in countries like India, Indonesia, Bangladesh, Myanmar, etc., during the south-west monsoon season, as opposed to South East China, Japan, etc., during the north-east rainfall season.
Why does India, have a Monsoon-type of Climate?
The Rann of Kutch in the west to Mizoram in the east divides the Indian area into two parts as the Tropic of Cancer runs across the heart of the nation. The southern half of the nation, which is in the tropical zone, is where the Tropic of Cancer is located.
Mountains with an average height of 6000 metres cover much of Indian Territory’s northern portion. The Himalayas block the entry of the cold winds from Central Asia into the subcontinent.
Pressure and Winds
Pressure and Surface winds, upper air circulation, Western cyclonic disturbances, and tropical cyclones are the atmospheric conditions that govern the climate and accompanying weather conditions in India.
North-East Trade winds
During the cold weather season, the North-East Trade Winds, which are constant winds that travel from land to sea, pass over India. Because the North-East trade winds carry so little moisture, they produce extremely little rainfall.
- Westerly flow, which mostly consists of the jet stream, controls the upper air circulation in the southwest region.
- Jet Stream: Also known as the Subtropical Westerly Jet Stream, jet streams are almost always found over 27° to 30° north latitude..
- The Jet stream’s speed fluctuates from approximately 110 km/h in the summer to 184 km/h in the winter.
- Western Cyclonic Disturbances: During the winter, the westerly flow from the Mediterranean region causes the western cyclonic disturbances.
- The weather in India’s north and northwest is typically influenced by the western cyclonic disturbances..
Features of Monsoon in India
India’s monsoon season is characterised by its predominant relief (orographic), unpredictability, and variable rainfall patterns, which frequently cause floods and droughts. When it rains, it does so unevenly and occasionally early and occasionally late (Some regions receive over 200 cms of rain and suffer from floods while others receive less than 50 cms annually and experience semi-desert conditions).
Rainfall during the monsoon season, which lasts from June to September, is seasonal. Rainfall’s spatial distribution is greatly influenced by relief or topography. For example, the windward side of the Western Ghats records more than 250 cm of precipitation. Once more, the Eastern Himalayas and the hill ranges in the northeastern states are to blame for the region’s excessive rainfall. Rainfall in various sections of the Western Ghats and North-East India ranges from 20 cm in western Rajasthan to more than 400 cm.
With growing distance from the sea, monsoon rainfall tends to decrease. As one branch of the monsoon enters from the eastern side, rainfall diminishes on the plains from east to west. Only 56 cm is delivered to Delhi, 76 cm to Allahabad, and 119 cm to Kolkata.
Rainfall pauses are associated with cyclonic depressions that originate mostly near the Bay of Bengal’s head and cross into the continent. The passage that follows these depressions, in addition to their frequency and intensity, influences the location of where rain falls. The rains can finish much earlier than expected, severely damaging standing crops and complicating the sowing of winter crops.
Mechanism of Monsoon in India
Onset of the South-West Monsoon
With the apparent movement of the Sun, the ITCZ’s location moves both north and south of the equator. The ITCZ moves northward in June as the sun shines vertically over the Tropic of Cancer. Under the influence of Coriolis force, the southeast trade winds of the southern hemisphere cross the equator and begin to blow in a southwest to northeast direction.
As the winds pass over the warm Indian Ocean, they pick up moisture. The Indo-Gangetic Plain, where the ITCZ shifts to in July, receives a south-west monsoon that blows from the Arabian Sea and the Bay of Bengal. This position of the ITCZ is known as the Monsoon Trough.
The phenomena of the westerly jet stream leaving its position over the north Indian plain, south of the Himalayas, is likewise connected to the change in the ITCZ’s location. Only when the western jet stream has left the area does the easterly Jet Stream (Somali Jet) begin to develop along 15°N latitude. The burst of the Indian monsoon is attributed to this easterly jet stream. The relief and thermal low pressure over northwest India change the winds’ southwesterly direction as they near the land. Two branches of the monsoon approach the Indian continent:
- The monsoon winds have an Arabian Sea branch that starts there.
- The Arakan Hills along Myanmar’s coast redirect a significant section of the Bay of Bengal branch toward the Indian subcontinent. As a result, the monsoon approaches West Bengal and Bangladesh from the south and southeast rather than the south-west.
Rainfall tends to “break” during the monsoon, which is another characteristic connected to it. Rainfall during the monsoon season only lasts a few days at a time. There are stretches without rain in between them. These monsoon breaks are a result of the monsoon trough moving.
Retreating Monsoon in India
There are sunny skies and an increase in warmth as the southwest monsoon season retreats. The soil is still damp. The weather becomes somewhat unpleasant as a result of the high temperature and humidity. This is often referred to as the “October heat.”
The mercury starts to drop quickly in the second half of October, especially in northern India. While the eastern section of the Peninsula experiences rain, north India experiences dry weather as the monsoon retreats. The wettest months of the year in this area are October and November.
The passage of cyclonic depressions that originate over the Andaman Sea and successfully traverse the eastern coast of the southern Peninsula is linked to the widespread rainfall during this season. These tropical cyclones cause a lot of damage.
These depressions and cyclones are primarily responsible for the majority of the rainfall along the Coromandel Coast. The northeast monsoon is essential for farming and water security in the south, unlike the rest of the country, which receives rain during the southwest monsoon season between June and September.
Monsoon in India Classical Theory
Scriptures like the Rig Veda make reference to the monsoon. The monsoon system, however, was not mentioned in these books. Arab traders conducted the initial monsoon winds scientific study. Monsoon patterns were crucial to Arab traders who travelled to India by sea and conducted business there.
An Arab explorer named Al Masudi described how the monsoon winds and ocean currents across the north Indian Ocean reversed in the eleventh century. Sir Edmund Halley explained the monsoon as the result of thermal disparities between continents and oceans as a result of their differential heating in the seventeenth century..
Monsoon in India Modern Theory
In addition to differential heating, the form of the continents, mountains, and the characteristics of air circulation in the upper troposphere all have an impact on the development of the monsoon (jet streams). Therefore, new ideas based on air masses and the jet stream is becoming increasingly important, while Halley’s theory has lost much of its value.
Monsoon in India Air Mass Theory
This idea holds that the monsoon is only a tropical region’s planetary winds modified. The notion is based on the ITCZ’s seasonal migration. Near the equator, the southeast trade winds from the southern hemisphere and the northeast trade winds from the northern hemisphere converge. The Inter-Tropical Convergence Zone is where these winds converge (ITCZ).
Monsoon in India Jet Stream Theory
Tibet’s highlands split the subtropical westerly jet stream throughout the winter. The northern branch reaches 20N–35N. Occasionally, the tropical easterly jet stream (TEJ), which diverges from the anticyclone generated over Tibet, reaches the southernmost point of Peninsular India. Jet-speed winds have also been reported over other peninsular regions.
As it descends over the Indian Ocean, the Mascarene High, a high-pressure cell, grows stronger. The onshore winds begin to blow in the direction of the thermally induced low-pressure area that has formed in the northern section of the Indian subcontinent from this high-pressure cell. Such winds change direction once they approach the equator, becoming south-westerly and known as the southwesterly summer monsoon.
Importance of Monsoon in India
In India, a number of dams, reservoirs, rivers, and canals are rain-fed and reliant on the monsoon season. The amount of rainfall has a direct impact on forestry and fisheries as well as other economic activities. In addition to providing relief from the intense and unpleasant summer heat, monsoon rain also revitalizes the living ground.
The monsoon also contributes to India’s social and cultural cohesion. Indians eagerly await the monsoon rains, especially the farmers. We are aware that the monsoon winds bring water for numerous agricultural pursuits. The monsoon phenomenon governs the agricultural calendar as well as the social-cultural life of the populace, including their celebrations, and in a way connects the Indian people together.
Numerous harvest celebrations are held across our nation to commemorate a successful harvest, including Bihu in Assam, Pongal in Tamil Nadu, Poonam in Kerela, and Lohri in Punjab. If the monsoon succeeds, it brings famines and a year of misery for everyone; if it fails, the entire country goes celibate. A rhythmic cycle of seasons is also provided by the seasonal changes in the wind systems and the associated weather conditions.
Monsoon in India FAQs
Q How many monsoons are in India?
Ans. There are two types of monsoon in India: The southwest monsoon and the northeast monsoon.
Q Where are monsoons in India?
Ans. Around June 1, the southwest monsoon hits Kerala’s shore in the southern state. It typically touches down in Mumbai about ten days later, travels to Delhi by the end of June, and reaches the rest of India by the middle of July. Every year, there is significant discussion regarding when the monsoon will begin.
Q Which type of monsoon does India have?
Ans. The southwest and northeast monsoons are the two monsoons that occur in India. The primary monsoon, known as the southwest monsoon, arrives from the sea in early June and begins to move up India’s west coast. Most of the nation is submerged in rain by mid-July.
Q What are the 4 types of monsoon?
Ans. The 4 types of monsoon are:
- Winter Season
- Summer Season or Pre-Monsoon Season
- South-West Monsoon Season
- North-East Monsoon or Post-Monsoon Season.
Q What causes monsoon in India?
Ans. Warm, humid air from the southwest Indian Ocean rushes toward nations like India, Sri Lanka, Bangladesh, and Myanmar as winter comes to a conclusion. These places experience a humid environment and intense rainfall during the summer monsoon.
Q Which country is known as land of monsoon?
Ans. India is known as the Land of monsoons
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