Context:
The India Meteorological Department has issued warnings about severe heatwave conditions impacting large parts of eastern India and the Gangetic Plain, following the waning phase of the strong El Niño of 2023. This underscores the complexity of assessing the impact of global warming on local weather patterns, with the presence of anticyclones intensifying the severity of heatwaves in affected regions.
Relevance:
GS I: Geography
Dimensions of the Article:
- Role of Heat Waves in Global Warming
- Anticyclones
- Impact of Anticyclones on Weather Patterns:
- Recent Impact of Anticyclones
Role of Heat Waves in Global Warming:
- Heat waves are a consequence of climate change, primarily caused by the emission of Greenhouse Gases (GHGs) from burning fossil fuels.
- These gases trap heat energy in the atmosphere, leading to an increase in both average and extreme temperatures.
- Human activities have contributed to a 1.2 degrees Celsius rise in global temperatures since pre-industrial times, making extreme heat events more intense.
- Global warming results in uneven temperature changes across regions, affecting the frequency and intensity of heat waves locally.
- Understanding these local effects is crucial for accurate forecasting and effective mitigation strategies.
Anticyclones:
- Anticyclones are regions of high atmospheric pressure, opposite to cyclones (low pressure).
- Winds circulate clockwise around anticyclones in the Northern Hemisphere and counterclockwise in the Southern Hemisphere due to the Coriolis Effect.
- They bring stable, calm weather conditions with little wind and clear skies.
- Sinking air within anticyclones warms up and dries out, leading to reduced rainfall and humidity.
- Summer anticyclones are often associated with hot and sunny weather, while winter anticyclones can bring cold and clear conditions with morning frost.
Link Between Anticyclones and Heat:
- Anticyclones contribute to heat through their persistence and strength.
- During the pre-monsoon season, the Indian Easterly Jet (IEJ) and a strong westerly jet can create an anticyclonic pattern over the Indian Ocean and the Indian subcontinent.
- Strong anticyclones can bring dry and hot weather over many parts of India, while weaker ones result in milder conditions.
- The IEJ, a narrow belt of strong easterly winds in the mid-troposphere, influences weather patterns over peninsular India and the south Indian Ocean during the pre-monsoon season.
- Another example is the African Easterly Jet (AEJ), which occurs over West Africa during the summer months and is formed due to temperature contrasts between the Sahara Desert and the Gulf of Guinea.
Impact of Anticyclones on Weather Patterns:
- Strong Indian Easterly Jet (IEJ) years are associated with elevated near-surface temperatures and decreased moisture levels in India, while weaker IEJ years coincide with cooler and wetter conditions.
- The intensity of anticyclones in any given year is a critical determinant of their connection to heat waves and the broader issue of global warming.
- El Niño occurrences often lead to more robust and enduring anticyclones over the Indian subcontinent, resulting in prolonged and more severe heat waves.
- A comprehensive understanding of the prevailing climatic conditions characterized by cooler temperatures and robust, long-lasting anticyclones is essential for precise weather forecasting and timely alerts.
Recent Impact of Anticyclones:
- Recent anticyclonic circulations over the North Indian Ocean caused anomalous rainfall in Odisha in March 2024. Anticyclones, characterized by clockwise wind circulation and subsiding air, can create high-pressure heat domes.
- This phenomenon might have also contributed to the floods experienced in Dubai in April 2024.
-Source: The Hindu
