Explain the mechanism of monsoons.
Answers
Answer: Mechanism of Monsoon involves the following concept. a phenomena of monsoon refer to a seasonal reversal of winds. It is because while the South West Monsoon winds blow from sea to land at the end of the summer season, the North east winds blow from land to sea during the winter season.
The term monsoon has been derived from the Arabic word mausin or from the Malayan word monsin meaning ‘season’. Monsoons are seasonal winds (Rhythmic wind movements)(Periodic Winds) which reverse their direction with the change of season. The monsoon is a double system of seasonal winds – They flow from sea to land during the summer and from land to sea during winter. Some scholars tend to treat the monsoon winds as land and sea breeze on a large scale. Monsoons are peculiar to Indian Subcontinent, South East Asia, parts of Central Western Africa etc.. They are more pronounced in the Indian Subcontinent compared to any other region. Indian Monsoons are Convection cells on a very large scale.They are periodic or secondary winds which seasonal reversal in wind direction.India receives south-west monsoon winds in summer and north-east monsoon winds in winter. South-west monsoons are formed due to intense low pressure system formed over the Tibetan plateau. North-east monsoons are associated with high pressure cells over Tibetan and Siberian plateaus. South-west monsoons bring intense rainfall to most of the regions in India and north-east monsoons bring rainfall to mainly south-eastern coast of India (Southern coast of Seemandhra and the coast of Tamil Nadu.). Countries like India, Indonesia, Bangladesh, Myanmar etc. receive most of the annual rainfall during south-west monsoon season where as South East China, Japan etc., during north-east rainfall season.
Factors responsible for south-west monsoon formation
• Intense heating of Tibetan plateau during summer months.
• Permanent high pressure cell in the South Indian Ocean (east to north-east of Madagascar in summer).
Factors that influence the onset of south-west monsoons
• Above points +
• Subtropical Jet Stream (STJ).
• Tropical Easterly Jet (African Easterly Jet).
• Inter Tropical Convergence Zone.
Factors that influence the intensity of south-west monsoons
• Strengths of Low pressure over Tibet and high pressure over southern Indian Ocean.
• Somali Jet (Findlater Jet).
• Somali Current (Findlater Current).
• Indian Ocean branch of Walker Cell.
• Indian Ocean Dipole.
Factors responsible for north-east monsoon formation
• Formation and strengthening of high pressure cells over Tibetan plateau and Siberian Plateau in winter.
• Westward migration and subsequent weakening of high pressure cell in the Southern Indian Ocean.
• Migration of ITCZ to the south of India.