Why the Indian Monsoon doesn’t start in the north?

Introduction to the Indian Monsoon

The Indian Monsoon is a complex and important weather phenomenon that greatly influences the climate and agricultural patterns of the Indian subcontinent. It is characterized by a seasonal reversal of winds, resulting in a distinct wet and dry season. While the monsoon typically begins in the southern regions of India, it does not begin in the north. This intriguing phenomenon has puzzled scientists for decades, and several factors contribute to the pattern.

1. Geographical factors

One of the main reasons why the Indian monsoon does not begin in the north is the influence of geographical factors. The presence of the high Himalayan mountain range acts as a significant barrier to the advancement of the monsoon winds to the north. The Himalayas obstruct the northward movement of moisture-laden winds, forcing them to deflect to the east and west.
In addition, the Tibetan Plateau, which lies north of the Himalayas, plays a crucial role in influencing the behavior of the monsoon. The plateau heats up during the summer months, creating a low-pressure system. This depression attracts moisture-laden winds from the Indian Ocean, initiating the monsoon over the southern regions of India. However, the terrain of the northern regions, characterized by the presence of the Himalayas and the plateau, prevents the monsoon from moving directly northward.

2. Temperature contrast and pressure gradient

Another important factor contributing to the delayed onset of the monsoon in the north is the temperature contrast between the landmass and the Indian Ocean. During the summer months, the landmass in northern India experiences intense heating, resulting in high temperatures. In contrast, the Indian Ocean maintains relatively lower temperatures due to its large body of water.
This temperature contrast creates a pressure gradient between the land and the ocean. The heated air over the land rises, creating a low-pressure system, while the cooler air over the ocean remains relatively high pressure. Monsoon winds flow from high to low pressure areas, and the pressure gradient drives the initial onset of the monsoon over the southern regions. However, the temperature contrast is less pronounced in the northern regions, resulting in a delayed onset of the monsoon.

3. Orographic effect

The orographic effect, influenced by the presence of the Himalayas, also plays a crucial role in preventing the monsoon from reaching the northern regions. As the moisture-laden winds approach the Himalayas, they are forced to climb the slopes of the mountains. As the air rises, it cools and condenses, resulting in the formation of clouds and precipitation on the windward side of the mountains.
This orographic lifting of air causes significant rainfall in the foothills and windward side of the Himalayas. As a result, much of the moisture is used up before the winds can reach the northern plains. The orographic effect acts as a barrier, limiting the northward progression of the monsoon and contributing to the delayed onset in the northern regions.

4. Interaction with westerlies

The interaction between the monsoon winds and the westerlies also influences the onset of the monsoon in the north. During the summer months, the westerlies, which are prevailing winds blowing from west to east, are present over the northern regions of India. These westerly winds oppose the northward advance of the monsoon winds, resulting in a delay in their arrival.

The westerlies exert a strong influence on the atmospheric circulation patterns, and their interaction with the monsoon winds can result in the formation of an atmospheric “barrier”. This barrier prevents the monsoon winds from penetrating further north, thereby inhibiting the onset of the monsoon in the northern regions.
In summary, the delayed onset of the Indian monsoon in the north is due to a combination of geographic factors, temperature contrast, orographic effect, and interaction with westerly winds. The presence of the Himalayas and the Tibetan Plateau, along with the associated orographic effect, acts as a significant barrier to the northward progression of the monsoon. In addition, the temperature contrast and the influence of the westerlies further contribute to the delayed onset. Understanding these complex interactions is critical for predicting and managing monsoon behavior and its impact on various sectors, including agriculture, in the northern regions of India.

FAQs

Why doesn’t the Indian Monsoon start in the north?

The Indian Monsoon doesn’t start in the north primarily due to the presence of the Himalayan mountain range.

How does the Himalayan mountain range affect the onset of the Indian Monsoon?

The Himalayan mountain range acts as a barrier that blocks the northward progression of the monsoon winds from the Indian Ocean.

What is the role of the Himalayas in diverting the monsoon winds?

The Himalayas force the monsoon winds to split into two branches – the Arabian Sea branch and the Bay of Bengal branch. These branches then follow the mountain range to the east and west, respectively.

Why does the Arabian Sea branch of the monsoon winds reach the Indian subcontinent earlier than the Bay of Bengal branch?

The Arabian Sea branch of the monsoon winds travels a shorter distance compared to the Bay of Bengal branch. As a result, it encounters less obstruction from the Himalayas and reaches the Indian subcontinent earlier.

What factors contribute to the delayed onset of the monsoon in the northern parts of India?

In the northern parts of India, the monsoon winds have to travel a greater distance and overcome the barrier of the Himalayas. These factors cause a delay in the arrival of the monsoon rains in the region.