Context:
According to recent studies, the changing character of Western Disturbances might be the primary cause of the abnormal winter seasons in India.
- India has not experienced a normal winter season in the past three years. The second wettest season in the country after the monsoons has remained unusually dry and hot.
Relevance:
GS I: Geography
Dimensions of the Article:
- Western Disturbances
- Importance and Issues related to Western Disturbances for India
- Impact of Western Disturbances on Winter in India
Western Disturbances
- Western Disturbances are a series of cyclonic storms that originate in the Mediterranean region and bring winter rains to northwest India.
- They travel a distance of over 9,000 km and collect moisture from the Mediterranean Sea, Black Sea, and Caspian Sea before hitting the western Himalayas.
- Western Disturbances traverse over Iran and Afghanistan before reaching India, mostly between December and April, due to the shift in the trajectory of the subtropical westerly jet stream.
- The jet stream carries the storm systems and its trajectory changes as per the position of the Sun. During the winter months, it shifts towards the rim of the Himalayas and moves from above the Himalayas to the Tibetan Plateau and China for the rest of the year.
Importance and Issues related to Western Disturbances for India:
Significance:
- Western Disturbances bring snowfall to the Himalayan region, which replenishes the glaciers during winter.
- These glaciers feed major rivers such as Ganga, Indus, and Yamuna and also numerous mountain springs and rivulets.
- These low-pressure storm systems support farmers in growing their rabi crop.
Issues:
- Western Disturbances can cause extreme weather events like floods, flash floods, landslides, dust storms, hail storms, and cold waves.
- Such events can cause severe damage to infrastructure and impact the lives and livelihoods of people.
Impact of Western Disturbances on Winter in India
Decrease in rainfall:
- In December 2022, the northwest region of India received 83% less rainfall than usual.
- In February 2023, the region received a 76% rainfall deficit.
Severe cold waves and cold days:
- Absence of Western Disturbances caused cold northern winds from the Himalayas to flow down, resulting in severe cold waves and cold days in December 2022 and most of January 2023.
Crop damage, fog and flash floods:
- Western Disturbances are responsible for hailstorms that damage standing crops.
- Fog events that interrupt air, rail and road services.
- Cloud bursts that result in flash floods can also be attributed to Western Disturbances.
-Source: Down to Earth
