Mains Practice Questions

Approach

• Start your answer by discussing the role of western disturbance in causation of cold waves.
• Discuss how La Nina affects the severity of cold wave.
• Conclude accordingly.

Introduction

• A cold wave is a rapid fall in temperature within 24 hours to a level requiring substantially increased protection to agriculture, industry, commerce, and social activities.
• The criteria required for Cold wave formation in India as per the Indian Meteorological Department (IMD) are:
  • Minimum temperature recorded by a meteorological station on the plains must be 10 degrees Celsius or less.
  • For high-altitude hills, the minimum must be below or at 0 degrees.
  • The highest temperature must be 4.5-6.4 degrees Celsius below normal.

Body

• Western disturbances are weather systems that originate in the Mediterranean region and play a critical role in the meteorology of the Himalayan region, including India.
  • These weather systems can cause a variety of extreme weather events such as crop damage, landslides, floods, avalanches, cold wave conditions and dense fog.
• Role of Western Disturbances in causing Cold Waves in India:
  • As the western disturbance moves towards India, it brings with it moisture-laden winds which replace chilly and dry northwesterly winds with warm and wet easterly breezes.
  • This change in wind direction can lead to a drop in temperature and the formation of cold waves.
  • Additionally, the excessive precipitation caused by western disturbances can lead to dense fog, which can further reduce visibility and increase the severity of the cold wave conditions.
• La Nina and Cold Waves:
  • La Nina is a weather phenomenon characterized by cooler-than-average sea surface temperatures in the central and eastern tropical Pacific Ocean.
    • During La Nina episodes, the Indian monsoon is typically weaker, which can lead to less rainfall and an increased likelihood of droughts in India.
    • This can lead to a drop in temperature and the formation of cold waves.
    • Furthermore, the weaker monsoon can also lead to an increased frequency of western disturbances, which can further increase the likelihood and severity of cold wave conditions.

Conclusion

• Western disturbances play a critical role in causing cold waves in India. The moisture-laden winds and excessive precipitation caused by these weather systems can lead to a drop in temperature and the formation of cold waves.
  • Additionally, La Nina conditions can affect the severity of cold waves by weakening the Indian monsoon and increasing the likelihood of droughts.