Why in News?
The monsoon was delayed compared to its normal onset date of June 1, as it arrived over the Kerala coast on June 8 in 2023.
What is Monsoon?
- Monsoons are seasonal winds (Rhythmic wind movements or Periodic Winds) which reverse their direction with the change of season.
Read also:- Weather & Climate
Factors Influencing South-West Monsoon
- The landmass of India experiences low pressure due to the differential heating and cooling of land and water, while the seas around it experience comparatively high pressure.
- In summer, the position of the Inter Tropical Convergence Zone (ITCZ) shifts over the Ganga plain. The ITCZ, which is the equatorial trough normally positioned about 5°N of the equator, undergoes this shift.
- The presence of the high-pressure area, east of Madagascar, approximately at 20°S over the Indian Ocean. The intensity and position of this high-pressure area affect the Indian Monsoon.
- During summer, the intense heating of the Tibetan plateau results in the formation of strong vertical air currents and low pressure over the plateau at about 9 km above sea level.
- During summer, the westerly jet stream moves to the north of the Himalayas, while the tropical easterly jet stream is present over the Indian peninsula.
What is the Onset of Monsoon?
- The onset of the monsoon over the Kerala coast marks the start of the four-month southwest monsoon season, which contributes to over 70% of India’s annual rainfall.
- Contrary to common assumptions, the onset does not refer to the first rain of the season, but rather the India Meteorological Department (IMD) sets specific technical criteria to determine it.
Conditions for Monsoon Onset
- The IMD determines the monsoon onset based on significant transitions in atmospheric and ocean circulations in the Indo-Pacific region.
- The declaration of onset relies on specific parameters related to rainfall consistency, intensity, and wind speed.
Read also:- Factors Determining Climate of India
Why monsoon delayed in India?,Why monsoon delayed in India?