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Can Artificial Rain fix Delhi’s Air Pollution Problem
Context:
Delhi’s AQI reached 492, with some areas hitting the maximum index value of 500, despite Stage IV GRAP measures.Looking at the gravity of the situation Delhi’s Environment Minister requested the central government for artificial rain.
About Artificial Rain or Cloud Seeding:
What is Cloud Seeding?
Cloud seeding is a weather modification technique designed to induce rainfall by introducing substances into the atmosphere that act as cloud condensation or ice nuclei. The most commonly used agents include silver iodide, potassium iodide, and sodium chloride. These substances encourage the formation of larger cloud droplets or ice crystals, increasing the likelihood of precipitation.
How It Works:
- Natural Rain Formation: Clouds form when water vapour condenses around particles in the atmosphere, creating droplets. These droplets collide, grow heavier, and eventually fall as rain.
- Seeding Process: Cloud seeding accelerates this natural process by injecting seeding agents into clouds using aircraft or ground-based generators. The chemicals stimulate droplet or crystal growth, causing rain to form and fall.
Conditions Required for Cloud Seeding
- Presence of Clouds: Cloud seeding requires sufficient cloud cover, with a particular depth and liquid water content. Without adequate clouds, the process is ineffective.
- Cloud Properties: The ideal clouds for seeding are those with:
- Sufficient Liquid Water Content: Essential for droplet growth.
- Appropriate Height: Mid-level clouds are typically most effective.
- Seasonal Challenges:
- Delhi’s winter atmosphere, characterised by low moisture and stable air, poses a challenge:
- Western Disturbances: These weather systems originating in the Caspian or Mediterranean Sea are necessary to disrupt atmospheric stability and create cloud cover during winter.
- Day-Specific Feasibility: Successful cloud seeding depends on real-time evaluations of cloud properties, such as liquid water content and altitude, using meteorological tools like radars.
Can Cloud Seeding or Artificial Rain Fix Air Pollution?:
- Limited Effectiveness: Cloud seeding is not a guaranteed solution for pollution:
- Temporary Relief: While prolonged rainfall can significantly reduce particulate matter like PM2.5 and PM10, its effect on gaseous pollutants such as ozone and sulphur dioxide is minimal.
- Uncertain Outcomes: The World Meteorological Organisation estimates that cloud seeding increases precipitation by only 0–20%, primarily under favourable weather conditions.
- Environmental Risks:
- Chemical Residues: Substances like silver iodide can accumulate in soil and water, potentially harming ecosystems and agriculture.
- Unknown Long-Term Effects: The broader environmental impacts of these chemicals remain unclear.
- Ethical and Resource Concerns:
- Rain Redistribution: Artificial rain in one region may reduce precipitation in others, potentially causing water scarcity.
- Weather Manipulation: The ethical implications of altering natural weather patterns are significant.
Challenges and Limitations of Cloud Seeding in Delhi:
- Weather Constraints
- Low Moisture Levels: Delhi’s winter air lacks the moisture needed for effective seeding.
- Stable Atmosphere: The stable winter atmosphere hinders cloud formation, making seeding feasible only during western disturbances.
- Temporary Impact: Artificial rain offers only short-term relief from pollution without addressing root causes such as vehicular emissions, industrial pollution, and stubble burning.
- Environmental Risks: The chemicals used in cloud seeding may lead to unintended ecological consequences, including soil and water contamination.
Alternative Solutions:
While artificial rain has its limitations, there are more sustainable approaches to address Delhi’s air pollution crisis:
- Source Control:
- Tackle Emissions: Enforce stricter controls on vehicular emissions and industrial pollution.
- Reduce Stubble Burning: Promote alternatives like crop residue management and bio-decomposers.
- Enhanced Measures:
- Strengthen GRAP Enforcement: Increase monitoring and ensure compliance with the Graded Response Action Plan.
- Sustainable Urban Practices: Encourage public transport, carpooling, and non-motorised transport options.
- Natural Solutions:
- Afforestation: Increase green cover to act as natural air purifiers.
- Urban Greening: Promote rooftop gardens and vertical greenery in densely populated areas.
