General Studies (Paper - 1) : Model Question & Answers

Question: What are ‘Western Disturbances’? How do they influence India’s weather?

Answer: Western Disturbances are low-pressure systems (temperate cyclones) embedded in the Westerlies, the planetary winds that flow from west to east between 30^o - 60^o latitude. These generally originate in the Mediterranean region and travel over Iran, Iraq, Afghanistan and Pakistan to enter India loaded with moisture. The frequency of these systems reaching India increases during winter with the southward shift of pressure belts (with the apparent movement of sun towards the tropic of cancer).

These disturbances generally lead to

• Mild rain during winter (beneficial to the rabi crop)

• Snowfall in Western Himalayas

• Cold wave in the region

• Sometimes hail formation

These disturbances generally affect North-west India but occasionally their effects go farther east and south (upto Central India). But in the recent past, it is observed that this beneficial weather phenomenon is increasingly becoming disastrous. The cloud burst in Leh in 2010, the floods and landslide in Uttarakhand in 2013 and the excessive rain in J&K in 2014 were all linked to these disturbances.

These disturbances originate thousands of kilometres away and travel over countries where data collection is sparse. More of these disturbances are now being observed these days because the technology to detect, monitor and predict has improved. Indian Meteorological Department is now undertaking studies to understand Western Disturbances.