Context:
Recently, strong Western Disturbances brought snow to parts of Himachal Pradesh, Uttarakhand causing changes in weather.
Western Disturbances:
- Extra-tropical storms originating in the Mediterranean region.
- Bring sudden winter rain to the north-western parts of the Indian subcontinent.
- Formation:
- Originate in the Mediterranean Sea as extra-tropical cyclones.
- High-pressure area over Ukraine and neighbouring regions consolidates, causing cold air intrusion from Polar Regions towards warmer, moist areas.
- Favourable conditions for cyclogenesis in the upper atmosphere promote the formation of eastward-moving extra-tropical depressions.
- Travel across the Middle East from Iran, Afghanistan, and Pakistan to enter the Indian subcontinent.
- Carried eastward by westerly winds (Subtropical Jet Stream).
- Weather Impact:
- Bring rain, snow, or hailstorms to northern and north-western India.
- Associated with cloudy skies, higher night temperatures, and unusual rain
- .Crucial for Rabi crops (e.g., wheat, mustard) and replenishing glaciers in the Himalayan region.
- Can cause crop damage, landslides, floods, and avalanches if excessive.
Read more about: Tropical Cyclones, Typhoons
Source: Financial Express
Previous Year Question
In the South Atlantic and South-Eastern Pacific regions in tropical latitudes, cyclones do not originate. What is the reason?
[UPSC Civil Service Exam – 2015 Prelims]
(a) Sea surface temperatures are low
(b) Inter-Tropical Convergence Zone seldom occurs
(c) Coriolis force is too weak
(d) Absence of land in those regions
Answer: (b)