In essence, monsoons are seasonal winds that change direction as the seasons change. Thus, they are cyclical winds. The monsoons are a twofold system of seasonal winds because they move from the sea to the land in the summer and from the land to the sea in the winter. The monsoons have always played a significant role because traders and mariners have relied on them to go.
India experiences northeast monsoons in the winter and southwest monsoons in the summer. The emergence of an extremely low-pressure system over the Tibetan Plateau is what causes the former to occur. The latter results from the formation of high-pressure cells across the Tibetan and Siberian plateaus.
Causes of a monsoon
Sunlight warms both land and ocean surfaces in the summer, but land temperatures rise faster because the land has a smaller heat capacity. An area of low-pressure forms as a result of the air above the earth expanding as it warms up. The air above the water continues to be at a greater pressure because it continues to be warmer than the land. This deficit in pressure over the continent causes winds to blow in an ocean-to-land circulation because winds move from high-pressure locations to low-pressure areas (a sea breeze). Moist air is transported inland by winds that blow from the ocean to the land. Because of this, summer monsoons produce a lot of rain.
- Southwest Monsoon: Due to extreme summer warmth and a persistent high-pressure cell in the southern Indian Ocean, it is brought on by intense low-pressure formation over the Tibetan Plateau. Most of the country experienced severe rainfall brought on by SW monsoon winds.
- Northeast Monsoon: High-pressure cells over the Tibetan and Siberian Plateaus are to blame for it. Rainfall is brought to the nation’s southeast coast by NE monsoon winds.
Mechanism of Monsoon
The mechanism that causes the monsoon winds to move toward the Indian subcontinent is the heating of land and water throughout the summer. During the months of April and May, the sun shines vertically over the Tropic of Cancer, causing the vast landmass to the north of the Indian Ocean to become extremely warm. In the northwest of the Indian subcontinent, this leads to the development of an intense low-pressure system. The low-pressure cell draws the Southeast trade winds over the Equator because the pressure in the Indian Ocean to the south of the landmass is high as the water progressively warms up.
These circumstances aid in the Inter-Tropical Convergence Zone’s northward drift (ITCZ). The South-West Monsoon is essentially the continuation of the southerly trade winds that are diverted toward the Indian subcontinent after crossing the equator. Between longitudes of 40 and 60 degrees East, these winds cross the Equator.
The occurrence of the westerly jet stream leaving its position south of the Himalayas, over the North Indian plain, is connected to the movement of the Inter-Tropical Convergence Zone. On the 15th-degree North parallel, the easterly jet stream does not enter the area until the western jet stream has left. The Indian monsoon has exploded due to this easterly jet stream.
Effects of Monsoon
- The catchment areas of Himalayan rivers are flooded due to heavy rainfall, which causes the destruction of life and property.
- Approximately, 100-120 days is the duration of monsoon, i.e from June to mid-September. Some portions of the country, like Tamil Nadu, experience a major portion of rainfall from October to November.
- Regional variation of monsoonal rainfall is often spotted. Like less than 10 cm of annual rainfall in Western Rajasthan and Ladakh, whereas in Meghalaya it is over 400 cm.
- The latter portion of the monsoon is divided into two branches, one is the Bay of Bengal, and the other Arabian Sea branch.
- The withdrawal of monsoon is a gradual process, which is completed from the country by early December.
- Too little rainfall during the summer monsoon can cause dire conditions for farmers on the land, whereas too much rainfall can cause coastal waters to be unsafe and prevent fishermen to depend on fishing.
- The southwest monsoon is vital for the cultivation of Kharif crops, which heavily depend on rainfall.
- The energy providers appreciate monsoons as they provide circulation of energy through heavy rainfall and strong winds.
