Wednesday, May 27, 2015

Western disturbance

Western disturbance (WD) is the term used to describe an eastward moving, extratropical storm that brings sudden winter rain and snow to the northwestern parts of the Indian subcontinent. The moisture in these storms usually originates over the Mediterranean sea and Atlantic Ocean. The passage of a WD across north India increases monsoon activity over Punjab and Uttar Pradesh. WD are important to the development of the rabi crop in the northern subcontinent.

The frequency of western disturbance amplified because of presence of easterlies from Bay of Bengal. Also due to pronounced warming over the Tibetan plateau in recent decades which can be attributed to climatic warming, favours enhancement of meridianal temperature gradients. The warming in recent decades over west central Asia led to an increase in instability of the western winds thereby increasing WDs leading to a higher intensity for heavy precipitation.

Such disturbances can damage crops resulting into economic as well as agricultural loss for the people and farmers. Farm output is affected when crops that are ready to be harvested or about to ripen, get soaked in excessive rainfall. This is a concern in states like Madhya Pradesh, Gujarat, Maharashtra and Rajasthan, Punjab and Haryana. though the effect cannot be said firmly but certainly the disturbances in monsoonal pattern in India will affect its citizens.

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