Seeding hope: Cloud seeding’s role in combating drought and water scarcity

What is cloud seeding?

• Cloud seeding is a weather modification technique aimed at enhancing precipitation (rainfall/snowfall) by dispersing certain substances into clouds that serve as cloud condensation or ice nuclei.
• Common agents: Silver Iodide, Potassium Iodide, Dry Ice (Solid CO₂) and Liquid Propane.
• Sometimes salt particles are used, especially in coastal regions.

How it works? (Mechanism)

1. Cloud selection: Only works on moisture-bearing clouds.
2. Seeding agents dispersed: Through aircraft, rockets or ground-based generators.
3. Process:

• Hygroscopic seeding (salt-based) → enhances droplet formation.
• Glaciogenic seeding (silver iodide) → promotes ice crystal formation.

4. Outcome: Accelerates condensation → increases rainfall/snowfall.

Types of cloud seeding

1. Static seeding – Enhances rainfall by adding particles to encourage droplet growth.
2. Dynamic seeding – Aims to boost vertical air currents for larger cloud development.
3. Hygroscopic seeding – Uses salts to absorb moisture and enlarge droplets.

Applications

• Rainfall augmentation – to combat drought, water scarcity and groundwater depletion.
• Snowpack increase – in mountains to sustain river flows (used in USA).
• Hail suppression – preventing crop damage.
• Fog dissipation – especially around airports.

Global scenario

• USA & Canada – for increasing snowpack in Rockies.
• China – large-scale cloud seeding (notably during 2008 Beijing Olympics).
• UAE – invests heavily in cloud seeding to secure water resources.
• Australia, Thailand, Israel – regular use in drought-prone areas.

India’s context

• States practicing/experimenting: Karnataka, Maharashtra, Andhra Pradesh, Tamil Nadu, Rajasthan.
• Notable example:
• Maharashtra (2015) conducted cloud seeding during severe drought.
• Karnataka (2017) “Varshadhare Project” for rain augmentation.
• Institutions involved: Indian Institute of Tropical Meteorology (IITM), Pune; ISRO supports with satellites.

Advantages

• Helps in drought management and agriculture.
• Ensures water security in arid regions.
• Reduces hailstorms → protects crops.
• Can help reduce air pollution (by inducing rain to wash pollutants).

Limitations/concerns

• Scientific uncertainty: Effectiveness ranges only 10-20% (ideal conditions).
• High cost: Aircraft, chemicals and operations are expensive.
• Environmental issues:
• Silver iodide toxicity (bioaccumulation risk).
• Altering natural weather cycles.
• Ethical & geopolitical concerns:
• “Weather modification as weapon” fears.
• Transboundary rainfall disputes (e.g., if rainfall shifts from one region to another).
• Legal vacuum: No comprehensive international law on artificial weather modification.

Cloud seeding is an artificial weather modification technique to induce rainfall/snowfall, offering potential in drought mitigation but limited by high costs, uncertain results, and environmental-ethical concerns, making it a debated yet significant climate-adaptation tool.