Monsoon

Monsoon

Monsoon

• • India’s climate is referred to as “monsoon” type. This type of climate is primarily found in the southeast and south of asia. 
  • The monsoon season in India is divided into two of the country’s four seasonal divisions, namely.
  • The southwest monsoon season – The southwest monsoons bring with them seasonal rainfall, which falls between June and September.
  • The retreating monsoon season – The monsoon is known to retreat during the months of October and November.

Factors Influencing South-West Monsoon Formation

• • The landmass of India experiences low pressure due to the differential heating and cooling of the land and water, whereas the surrounding seas experience relatively high pressure. 
  • The summertime shift in the Inter Tropical Convergence Zone (ITCZ) position over the Ganga plain, an equatorial trough typically located approximately 5°N of the equator. 
  • During the monsoon season, it is also referred to as the monsoon-trough.

Inter Tropical Convergence Zone

• • The broad trough of low pressure in equatorial latitudes is known as the Inter Tropical Convergence Zone (ITCZ). 
  • The trade winds from the northeast and southeast converge here.
  •  This convergence zone follows the apparent movement of the sun, moving north or south, but it is roughly parallel to the equator.
  • The high-pressure area over the Indian Ocean, roughly located at 20°S, is present east of Madagascar.
  •  The Indian Monsoon is influenced by the strength and location of this area of high pressure.
  • Summertime temperatures on the Tibetan plateau are extremely high, causing strong vertical air currents and the development of low pressure over the plateau at a height of roughly 9 km above sea level.
  • The tropical easterly jet stream is present over the Indian peninsula during summer and the westerly jet stream moves north of the Himalayas. 
  • The Easterly Jet, also known as the African Easterly Jet.
  • Southern Oscillation (SO): The tropical eastern Indian Ocean typically experiences low pressure when the tropical eastern South Pacific Ocean experiences high pressure. 
  • However, there are years when the pressure patterns reverse, with the eastern Pacific having lower pressure than the eastern Indian Ocean. 
  • The SO is the name given to this recurring shift in pressure conditions. 

El Nino

• • This is the term used to describe the occurrence of a warm ocean current that periodically develops along Peru’s coast, temporarily replacing the cold Peruvian current. 
  • Since this current begins to flow during Christmas, “El Nino,” which translates from Spanish to mean “the child,” refers to the infant Christ.
  •  El Nino activity raises sea surface temperatures and reduces the strength of the trade winds in the area.

Mechanism

• • Onset of the South-West Monsoon
  • With the apparent movement of the Sun, the ITCZ location moves north and south of the equator. 
  • June is when the ITCZ moves northward and the sun crosses the Tropic of Cancer vertically.
  • 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 these winds pass over the warm Indian Ocean, they pick up moisture. 
  • The south-west monsoons blow from the Arabian Sea and the Bay of Bengal during the month of July, when the ITCZ moves to 20°–25° N latitude in the Indo-Gangetic Plain. 
  • This ITCZ is commonly referred to as the Monsoon Trough. 
  • The phenomenon of the westerly jet stream withdrawing from its position over the north Indian plain, south of the Himalayas, is also connected to the shift in the position of the ITCZ.
  • Only after the western jet stream has left the area does the easterly jet stream, also known as the Somali Jet, begin to move along latitude 15°N. 
  • The Indian monsoon’s sudden onset is attributed to this easterly jet stream.
  • The relief and thermal low pressure over northwest India change these winds’ southwesterly direction as they get closer to the land.
  •  There are two branches of the monsoon that approach the Indian landmass: 
  • The monsoon winds that originate over the Arabian Sea are known as the Arabian Sea branch.
    o The Arakan Hills on Myanmar’s coast divert a significant amount of the Bay of Bengal branch in the direction of the Indian subcontinent. 
  • As a result, the monsoon enters Bangladesh and West Bengal from the south and southeast rather than the south-west.
  • Rainfall tendencies to occur in “breaks” during the monsoon, which is another phenomenon linked to it.
  •  The monsoon rains only last a few days during the season. 
  • There are periods of time without rain in between them.
  •  The movement of the monsoon trough is connected to these monsoon breaks. 
  • Although the overall pattern is consistent, there are noticeable regional differences in the nation’s climate.

Retreating Monsoon Season

• • Clear skies and rising temperatures signal the end of the southwest monsoon season, although the land remains moist. 
  • The weather gets quite oppressive because of the high temperatures and humidity. The “October heat” is the term used to describe this.
  • The second part of October sees a sharp drop in temperature, especially in northern India.
    While the eastern part of the Peninsula experiences rain, the northern part of India experiences dry weather during the retreating monsoon. 
  • The wettest months of the year in this area are October and November.
  • The season’s abundant rainfall is linked to the movement of cyclonic depressions that begin over the Andaman Sea and traverse the eastern shore of the southern Peninsula. 
  • These tropical cyclones cause a great deal of damage. 
  • These depressions and cyclones provide the Coromandel Coast with the majority of its rainfall. 
  • The northeast monsoon is essential for farming and water security in the south, while the rest of the country receives rain during the southwest monsoon season, which runs from June to September.
    

Impact of Monsoons on Life in India

Positive

• • Approximately 64% of India’s population makes their living from agriculture, which is reliant on the monsoon season. 
  • India’s agricultural prosperity is heavily reliant on timely and sufficient rainfall. Agriculture suffers greatly if it fails, especially in areas without developed irrigation systems.
  • Different crops can be grown depending on the monsoon climate variations between regions.
  • The wide range of food, clothing, and home styles in India are indicative of the regional variations in the monsoon. 
  • The monsoon rains contribute to the recharging of reservoirs and dams, which is then utilized to produce hydroelectric power. 
  • In north India, winter rainfall from temperate cyclones is very helpful for Rabi crops. 

Negative

• • In certain regions of the nation, yearly droughts or floods are caused by variations in rainfall. 
  • In large parts of India, the problem of soil erosion is brought on by sudden monsoon bursts.
  • Abrupt rainfall in hilly regions can cause landslides, which in turn harms physical and natural infrastructure, disrupting human life on both an economic and social level.