The Indian monsoon is a complex phenomenon influenced by various climatic factors. Critically examine the role of oceanic and atmospheric factors in determining the intensity and distribution of monsoon rainfall in India.

• El Nino : is an oceanic-atmospheric interaction in Pacific ocean that affects monsoon. It is caused due to weakening of South East Trade winds.

• In Normal Year, the south East trade winds pull water towards the Australian Coast. → Thus, Darwin (in Australia) develops low pressure (LP) and due to upwelling of cold water, Tahiti (in Peru) develops high pressure.

→ However, during El Nino, the south East trade winds weaken. → Hence, warm waters are not pushed as much towards Australia and there is little upwelling of cold water in Peru. Thus, Peru remains warm → Thus, low pressure (LP) develops in Peru and HP develops in Australia. → The normal walker cell circulation gets disturbed and thus, there is little South west Monsoon in India. → Thus, El Nino has a negative impact on Indian monsoon.

DISTRIBUTION OF MONSOON RAIN IN INDIA :

→ Due to temperate cyclones in Mediterranean Sea, western disturbances cause monsoon in North India during winters. → In summer, due to south west monsoon winds, rain occurs in North India and East India. → However, due to western Ghats, Pune lies in rainshadow area. → Similarly, during winter, Tamil Nadu gets maximum rain due to North East trade winds.