Origin of monsoon

                     Origin of monsoon

The word monsoon is derived from the Arabic word mausim.  The monsoon was first used for the winds in the Arabian Sea, which move from the south-west in summer and from the north-east in winter.  Thereafter, all the winds in seasonal order on the globe were called monsoons.  The Indian subcontinent is completely under the influence of these winds.  The following concepts are important in understanding the origin of monsoon and its mechanism:

1. Thermal Concept- According to this concept, the monsoon winds are considered to be the largest form of aquatic and terrestrial wind, which arise due to the anomalous distribution of water and land.  Due to excessive sunlight in summer, the parts of the area become the center of low air pressure, then the parts of the sea side become low The winds become the centers of air pressure, then the winds move from the seas towards the site, which is called the summer monsoon.  In contrast, during winter, the parts of the place are colder than the seas and the centers of high pressure and the winds move from the site towards the sea, which is called winter monsoon.


General dates for the onset of southwest monsoon of India

2. Dynamic Concept - Sir Flon who is considered the originator of Dynamic Concept.  According to the monsoon winds originate due to the transfer of air pressure and wind boxes.  Convergence arises due to the mixing of commercial winds near the equator, which is called inter-tropical convergence.  In fact, the endotropic convergent convergence is an area of ​​low pressure that separates the north-eastern and south-eastern trading winds from each other. 

The northern convergence range expands to 30 ° northern latitude when the sun passes.  In south-east Asia, equatorial calm winds begin to run, which is the southwestern summer monsoon.  With this, cyclones, storms etc. are also activated.  In contrast, during winter, wind belt move south.  The northern convergence boundary from southeast Asia is removed when the sun is south and there the northeast the trade winds expand and this is the winter monsoon.

3. Jet Current Theory - This latest ideology of monsoon origin is based on the convection currents called jets in the troposphere, the lowest layer of the atmosphere.
The monsoon is, in fact, a complex wind system.  It is not merely a surface thermogenic communication.  In the troposphere above the northern and southern poles of the Earth, the polar vortices of air are produced, which help in the creation of monsoon on the ground.
Of Mb  In northern shell  Long winter nights Over the arctic region Located in the troposphere Very cold air Down due to heavy So that it sits  High on the ground the pressure is formed. At the same time troposphere high in surface Low over air pressure the pressure remains.  This types of upper surface low and around the air pressure. Cyclonic wind Flows  this High air cirulation towards on the equator. The part is called jet stream and its general direction is from west to east.  This jet stream flows between 20 and 35 "north latitude, making a turn. This jet stream in southern Asia commonly flows in a horizontal direction at an altitude of 12 km from the troposphere. It is divided into branches due to mechanical obstruction of the Himalayan Mountains and the Tibetan Plateau.
Its northern branch flows west to east in an arcular form in the north above the Tibetan plateau.  The main southern branch flows south of the Tibetan plateau and the Himalayas.  The main branch of the jet stream of the cyclonic path flowing over Afghanistan and Pakistan
Of the cyclonic route that occurred.  Follows  Hence.  Dynamic high pressure (anti-cyclone) over his right and Afghanistan and Pakistan Is generated.  The main branch of the westerly jet stream south of the Himalayas flows along the cyclonic curve (counterclockwise) due to mechanical obstruction, and a high-plane cyclone (low air pressure) is produced over the Tibetan plateau to the right of the jet stream.
In winter, tropospheric cyclonic conditions develop in Afghanistan, Pakistan and northwest India.  Hence winds start to sit down.  The atmosphere is stable and the weather remains dry and clean, but sometimes there are occasional changes in the weather.  From the Mediterranean Sea to the intermediate valley of the Ganges, there are occasional storms which cause scanty rainfall.  Except Tamil Nadu, the rest of India is generally dry.
After March, as the sun is Uttarayan, the jet stream also starts moving northwards.  In April and May, a thermally low air pressure center is formed over Pakistan and northwestern India, but the kinetic cyclone of the jet stream in the troposphere is sustained.  The air sits below the top and prevents the air from rising from the bottom (low pressure), so in April and May the low pressure extends to northwest India.  Below this, the thermogenic low air pressure has already developed.  Therefore, the upper air pressure is lower.  Draws upward winds.  Summer of India Monsoon rainfall is related to specific cyclonic vortices.  When the southeast trading winds cross the equator, their direction becomes southwest due to the Coriolis force (deflection).  Along with the inter-tropical convergence, kinetic waves in the form of a cyclonic vortex produce rain.  It is notable that the summer monsoon prevails more in southern Asia than the winter monsoon in East Asia.

 El Niño theory
Gilbert Walker has contributed significantly to the development of this theory.  In this theory, it is assumed that sea surface temperature has an effect on air pressure and winds.  This theory is based on the study of the surface water temperature of the Indian Ocean and Pacific Ocean between the Cancer and Capricorn lines.  Gilbert Walker stated that the Seesaw model is found in the pressure over the Indian Ocean and the Pacific Ocean.  When the air pressure over the Pacific Ocean is high, the pressure over the Indian Ocean is low and this situation is favorable for the Indian monsoon.  This process is known as Dakshin Oscillation.  The southern oscillation is also known as the 'Walker curve.  The rising air over Indonesia creates two Walker Chakras.  Under the first cycle, the rising air from Indonesia descends into central-eastern Pakistan and northwest India.  Similarly a second cycle is formed between Indonesia and the western coast of South America.  Rising above Indonesia, the air descends into the eastern Pacific Ocean.  Where the weakening of the first cycle is unfavorable for the Indian monsoon.  In fact, Indonesia (warm) and East Pacific coast (cold) provide the driving force to the Walker cycle.