Origin of Monsoon
The word monsoon is derived from an Arabic word ‘Mausim’ means season. Monsoon is such a seasonal wind which blow in one direction during summer but blow absolutely reverse during winter. origin of monsoon is just like a mystery. Though several theories are there to explain the origin of monsoon, but,certain phenomena such as burst of monsoon still can not be explained.The climate which is affected by monsoon is called as monsoon climate. This climate is generally found in both the hemisphere. South east Asian countries like India, Pakistan, Srilanka, Laos are belongs to monsoon climate.
Monsoon and India:
India is the land of agriculture and its economy dependent on monsoon wind. Monsoon bring huge rainfall throughout our country and makes the land greenery.
Origin of monsoon:
Several theories are there which explain the origin of monsoon.
- Alternating heating and cooling land and sea by Hailey1686
- Shifting of pressure belt by Flohn 1951
- Monsoon and Tibetan plateau by P Koteswaram 1953
- MONEX 1973
Hailey’s Theory 1686:
During summer sun rays become vertical over the tropic of cancer. That’s why temperature rises enormously over the land surface which responsible to make extreme low pressure on it. whereas high pressure is being developed over the Indian ocean due comparatively low temperature on it. Thus, moisture laden wind move from Indian ocean to land surface. It brings heavy rainfall all over India, sri lanka, Bangladesh and many more countries.
Flohn’s theory 1951:
Folhn put forwarded his ’Dynamic theory’ for the origin of monsoon in the year of 1951. According to him, monsoon is the result of shifting of pressure belts. He opined that during northern summer all the pressure belt shift towards the north. Because, during summer sun rays become vertical over the tropic of cancer, resulted the heat equator moves up to 5°N-10°N from its original position along with sub-tropical high pressure belt. Thus, the land surface of northern hemisphere getting heated gradually in comparison to its surrounding water bodies. Subsequently, low pressure and high pressure develops on the land surface and water bodies respectively, that given birth the monsoon wind circulation.
According to him existence of Asian monsoon is not the result of temperature contrast between land and sea, but, mainly due to the annual migration of thermally induced planetary wind and pressure belt under continental influence.
P koteswaram theory 1952:
P.kotewsaram observed that upper air circulation over the Tibet plateau plays an important role for monsoon. For this he tried to established the relationship between monsoon and the wind prevail over the Tibet plateau. During April and May excessive heating of this plateau bring huge rainfall, which release immense amount of latent heat over this plateau. This latent heat further mixed with sensible heat and produce an elevated heat island over this plateau at the height of 4km above from the sea level. Now the air rising rapidly and spread outward and sinks in the equatorial part of Indian ocean. Meanwhile,the rising air deflected right by the earth rotational force and move in anti clockwise which given birth anti cyclonic condition in the troposphere at the height of 9km-12km over Tibet. Now the outward moving wind blow towards the sea (Indian ocean) as low pressure prevails there. Thus, this wind collect huge moisture that bring immense rainfall over the Indian subcontinent.