Western Disturbances

In News

• Variations in the intensity and locations of the Western Disturbances have brought heavy rainfall to Delhi during some months and kept the city dry and in the grip of a heat wave at other times.

What is Western Disturbance (WD)?

• It is an extra-tropical storm that originates in the Mediterranean region.
  • The disturbance travels from the “western” to the eastern direction. 
    • Disturbance means an area of “disturbed” or reduced air pressure. 
    • Equilibrium exists in nature due to which the air in a region tries to normalize its pressure.
    • The WD is not always the harbinger of good weather.
• In the term “extra-tropical storm”, the storm refers to low pressure. 
  • “Extra-tropical” means outside the tropics (as WD originates outside the tropical region).

Impacts 

• It brings rainfall, snowfall, and fog to northern India.
• If winds (jet stream) flow from the west to east direction at an altitude of 30,000 feet then the weather will be stable in that region. 
• A jet stream is a river-like current of air circulating across the globe at upper levels of the troposphere.
• WD is important for the agriculture of the Rabi crop in the Northern subcontinent.
• WD brings winter and pre-monsoon rain and is important for the development of the Rabi crop in the Northern subcontinent.
• Sometimes WDs can cause extreme weather events like floods, flash floods, landslides, dust storms, hail storms, and cold waves, Dense fog, killing people, destroying infrastructure, and impacting livelihoods.

Source: IE