Why Is The Whole Of India Getting Rain, But Not Tamil Nadu?

The India Meteorological Department (IMD) has issued yellow and red alerts for several states. Rain wreaks havoc across North India. Many areas get flooded. The water level in the River Yamuna at Delhi’s Old Railway Bridge reached 207.33 metres on Friday. However, the water will recede further during the day, officials said.

Floodwaters have entered houses in the low-lying areas of Delhi. People residing here have been shifted to safer places. Punjab has confirmed widespread damage to crops and property, with nearly 3 lakh hectares of farmland under water. Death tolls rise in Uttarakhand and Himachal Pradesh.

As per an IMD report, between September 1 and 5, Delhi received 719.5 mm of rain, Punjab 581.4 mm, Himachal 948 mm, Jammu and Kashmir 687.3 mm, and Assam 826.6 mm. But the state of Tamil Nadu has not received rain. What is the reason behind Tamil Nadu being rain-starved during the Monsoon season? Here’s an analysis.  

What Is Monsoon?

The word monsoon is derived from the Arabic word Mausim, meaning ‘season’. Its literal meaning refers to a seasonal reversal of winds caused by several geographical patterns, such as differential heating and consequent pressure difference between sea and land.

(Source - IMD)

There are two types of Monsoons – the Southwest Monsoon and the Northeast Monsoon.

Monsoon Pattern In India

The Southwest Monsoon, India’s main rainy season, ranges from June to September. As per IMD, about 75 per cent of India’s total rainfall comes during this season. It usually begins in early June when the monsoon winds reach Kerala. Over the next few weeks, these winds spread across the entire country. But parts of Tamil Nadu are still rain-faded.

(Source - IMD)

When the southwest monsoon begins to lose its intensity, the northeast monsoon starts by October, which is also called the retreating monsoon. Although it is shorter and less widespread, it is important for southern India and brings rain to Tamil Nadu from October to December.

Why Is The Whole Of India Getting Rain, But Not Tamil Nadu?

Its answer can be found in monsoon dynamics and the geography of India. When the Southwest Monsoon enters India through the Kerala coast, it brings approximately. 90% of the annual rainfall in most of India, Tamil Nadu did not receive because it lies on the rain-shadow side of the Western Ghats.

Rainfall pattern in India (Source - IMD)

When the Northeast Monsoon blows from October to December, it brings moisture-laden winds from the Bay of Bengal. It gives Tamil Nadu approximately. 60% of its annual rainfall. This is the reason why most of India either gets flooded or receives enough rain in the June to September period, Tamil Nadu is relatively dry until the October to December period.

Geographers find other reasons too. They explain that the Western Ghats works as a blockage to the southwest monsoon clouds, causing the monsoon to move away from Tamil Nadu. It keeps Tamil Nadu dry in the main monsoon season.

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