Advancement of the Southwest Monsoon in India

• 01 Jun 2024

Source: TH

The Southwest Monsoon has set in over Kerala and advanced into most parts of Northeast India, indicating the onset and progress of the crucial rainy season in the subcontinent.

• There are several theories explaining the monsoon, such as the Thermal Theory (Edmund Halley), Dynamic Theory, Jet Stream Theory, ITCZ Theory, and Indian Ocean Dipole Theory. The simplest way to understand the process of the monsoon is through the Thermal Theory, which is provided below.
• The tropical monsoon climate is primarily caused by the differential heating and cooling rates of land and sea.
  • During the summer, when the sun is overhead at the Tropic of Cancer, large land masses in the northern hemisphere (Central Asia), heat up significantly, creating intense low-pressure areas.
    • Meanwhile, the surrounding seas, which warm up more slowly, remain relatively cool.
    • This pressure difference causes winds from the high-pressure region in the Southern Hemisphere (Australia) to blow towards the low-pressure areas, crossing the equator and transforming into the Southwest Monsoon as they reach the Indian subcontinent.
  • In winter, the situation reverses as the sun shifts to the Tropic of Capricorn. Central Asia cools rapidly, forming high-pressure areas, and winds blow outwards as the Northeast Monsoon.
    • These winds cross the equator and become the Northwest Monsoon in northern Australia. This seasonal reversal of wind directions characterises the tropical monsoon climate, resulting in distinct wet and dry seasons.

Read more: Monsoon