The Indian Monsoon

  • The Indian Monsoon
    08.07.2017 16:48


    What is the Indian monsoon and how does it form?

    A monsoon is a seasonal change in the prevailing wind direction. The Indian monsoon is initiated by a north-south gradient in both temperature and pressure. The continental land mass becomes warmer than the Indian Ocean which sets up a temperature gradient. There is then more surface heating and ascent of air over the land which leads to the formation of a surface low pressure system over India. Low pressure leads to cloud formation and therefore rain development, and also acts as a driver for the monsoon winds. The summer monsoon phenomenon occurs typically between June and September, and in India the summer monsoon acts as a key driver for rainfall and wind patterns.

    The importance of the monsoon
    The rainfall from the South Asian monsoon is vital for India, particularly during the summer months when 80% of the annual rainfall occurs. The most highly seasonal rainfall regime on earth significantly influences India's agriculture sector, power production and the frequency of droughts, which consequently leads to economic impacts.  

    What has happened this year?
    There are detrimental impacts to monsoon rainfall, including landslides and flooding, which can subsequently lead to fatalities. So far this year there have been 22 fatalities reported, due to various reasons including drowning, electrocution and injuries. North-eastern regions of the country have seen the greatest impacts, with around 400, 000 people displaced and reports say that the state of Assam is particularly affected with 17 out of the 35 districts flooded. 120mm of rainfall was recorded in a 24 hour period, in Chotabekra, West Bengal on Friday 7th July. Relief camps are able to help some, but it is difficult to reach people in remote areas. Water contamination and waterborne diseases are a concern, and access to safe water and sanitation is a key priority. Agricultural land has also been impacted, which will impact people’s livelihoods.

    Monsoons in previous years
    The performance of the monsoon is much-studied. The timing of the northward advance of the rain is a crucial cooling mechanism. Delay in the rainfall led to a heatwave in 2015, resulting in over 2000 deaths. Also in 2013, early monsoon rainfall led to around 5700 people being ‘presumed dead’ in northern parts of India.

    By: Sabrina Lee