Monsoon refers to a seasonal wind pattern characterized by a significant change in prevailing wind direction and intensity, which leads to distinct wet and dry seasons in certain regions, especially in the Indian subcontinent. In India, the southwest monsoon commences on the 15th of June, and the mechanism underlying its onset has been explained as follows:

Mechanism behind the Onset of the Indian Monsoon:

• Differential Heating: As the Sun’s rays strike the Earth, different surfaces heat up at varying rates. During summer, landmasses heat up faster than oceans. This causes the air above the land to warm and rise, creating a low-pressure area. Meanwhile, cooler air over the oceans creates a high-pressure area.
• Pressure Gradient: The contrast in pressure between the land and the ocean generates a pressure gradient. Air flows from areas of high pressure (oceans) to areas of low pressure (land), initiating the movement of air masses.
• Inter-Tropical Convergence Zone (ITCZ): In summer, the ITCZ, a low-pressure belt encircling the Earth near the equator, migrates northward due to the Sun’s apparent movement. This displacement leads to the convergence of trade winds from both hemispheres.
• Monsoon Trough: The northward shift of the ITCZ creates a trough of low pressure known as the “monsoon trough.” This trough serves as a conduit for the movement of moist air from the southern hemisphere to the northern hemisphere.
• Indian Ocean Influence: The warm waters of the Indian Ocean provide a source of moisture. As the monsoon trough approaches the Indian Peninsula, it draws in moisture-laden air from the Indian Ocean.
• Barrier of the Western Ghats: The Western Ghats, a mountain range along the western coast of India, acts as a barrier. Moist monsoon winds hit the mountains, are forced to rise, cool, and condense, leading to heavy rainfall on the windward side (southwest side) of the mountains.

Effect of ENSO on the Indian Monsoon:

• El Nino events, characterized by warmer-than-average sea surface temperatures in the central and eastern Pacific Ocean, can disrupt atmospheric circulation patterns and lead to suppressed monsoon rainfall, contributing to drought conditions and agricultural losses.
• Conversely, La Nina events, marked by cooler-than-average sea surface temperatures in the same region, tend to enhance the monsoon by intensifying atmospheric circulation, resulting in increased moisture inflow and higher-than-normal precipitation over India.
• Thus, El Nino and La Nina (collectively ENSO) exert a significant influence on the Indian monsoon.
• These interlinked oceanic and atmospheric phenomena underscore the intricate nature of the monsoon system and emphasize the need for understanding and predicting their occurrences to effectively manage the resultant impacts on agriculture, water resources, and regional economies.

Amidst growing unpredictability driven by climate change and altered oceanic dynamics, understanding and addressing climate impacts on the monsoon is crucial. Through scientific inquiry, technology, and community engagement, we can navigate this evolution, preserving its vital role in environmental renewal and societal well-being.