Air pollution in Delhi brings back an old concept — cloud seeding to induce artificial rain. In October 2025, the Delhi Government and IIT-Kanpur conducted cloud seeding trials to reduce pollution, but with limited success.
Surprisingly, this isn’t new — India’s first cloud seeding attempt was in 1951, and Delhi’s first trial happened in 1957.
📍 Why in News?
- 28 October 2025: Delhi & IIT-Kanpur conducted two cloud-seeding trials costing ₹60 lakh, using silver iodide & sodium chloride flares from a Cessna aircraft.
- Result: 0.3 mm rain in Noida–Greater Noida, but negligible rainfall in Delhi due to insufficient moisture.
- First experiment in Delhi dates back to 1957 by NPL’s Rain & Cloud Physics Research (RCPR) Unit.
🌩️ What is Cloud Seeding?
Cloud seeding is a weather modification technique used to enhance rainfall by dispersing certain chemicals into clouds to stimulate precipitation.
Agents Used
| Type | Chemical Substance | Purpose |
|---|---|---|
| Glaciogenic | Silver Iodide (AgI) | Forms ice crystals |
| Hygroscopic | Sodium Chloride (NaCl), Potassium Chloride | Helps water droplets grow |
Mechanism (Easy UPSC):
Cloud seeding does not create clouds → it enhances rain from existing clouds.
You need at least 50% moisture & suitable clouds for success.
🧪 India’s First Cloud Seeding Experiments: A Historical Timeline
| Year | Event | Organisation |
|---|---|---|
| 1951 | First trial in Western Ghats | Tata Group |
| 1952 | Salt & AgI used via balloons | IMD |
| 1955 | RCPR Unit set up in Delhi | NPL |
| 1957–59 | First Delhi trials (ground generators) | NPL-RCPR |
| 1967 | Unit shifted to Pune | IITM |
Did you know?
The 1957 Delhi trial used ground sprayers, not aircraft — to push salt particles into clouds.
Also Read: Extreme Cold Expected in India: Understanding the “La Niña
📍 Case Study: 1957 Delhi Cloud Seeding Trial
- Conducted during monsoon (Jun–Sept) to ensure required cloud moisture
- Used two ground-based sprayers dispersing salt solution for 3 hours
- Findings (Mausam Journal, 1961):
- Rain recorded on some days, but inconclusive results
- Hard to separate natural rainfall vs. seeding effect
Reasons for limited success back then
✅ Limited atmospheric data
✅ No aircraft technology
❌ Hard to target right cloud at right time
🔬 Why Cloud Seeding is Uncertain?
Even World Meteorological Organization (WMO) states that scientific certainty is low due to:
- Highly variable atmospheric conditions
- Difficulty in controlling seed dispersion
- No guarantee of rainfall amount or location
It works best in water-deficient, semi-arid areas, not polluted urban skies.
🚧 Challenges with Cloud Seeding in India
| Challenge | Explanation |
|---|---|
| Moisture Dependence | Needs right cloud type, height & humidity |
| High Cost | Aircraft-based seeding is expensive |
| Toxicity Concerns | Silver iodide may affect soil & aquatic life |
| Short-Term Fix | Not a long-term solution for drought or pollution |
🇮🇳 Where Has India Attempted Cloud Seeding?
- Maharashtra, Karnataka, Andhra Pradesh, Tamil Nadu for drought relief
- Delhi NCR (2024) for pollution reduction
- Himachal & Uttarakhand for snow enhancement
- IITM Pune leads current research
🌆 Conclusion
Cloud seeding is not a magic solution — it is a conditional weather modification technique with limited predictability. While it may provide temporary relief, especially during drought or pollution spikes, scientific uncertainty remains high, and long-term strategies must prioritise renewable solutions, pollution control, and sustainable water management.
Also Read:Air Pollution in India – Causes, AQI & UPSC Notes
📝 Mains Practice Question (10 marks)
“Artificial rain through cloud seeding is not a sustainable solution to India’s environmental challenges. Critically examine.”
🎯 Prelims Practice MCQs
Q1. Cloud Seeding requires which of the following conditions?
- Sufficient moisture in clouds
- Presence of hygroscopic nuclei
- Clear sky with no cloud formation
Select the correct answer:
A) 1 & 2 only ✅
B) 2 & 3 only
C) 1 & 3 only
D) 1, 2 & 3
Q2. Which of the following chemicals are commonly used for cloud seeding?
- Silver Iodide
- Sodium Chloride
- Urea
Options:
A) 1 & 2 only ✅
B) 2 & 3 only
C) 1 & 3 only
D) 1, 2 & 3
Q3. Cloud Seeding was first introduced in India in which region?
A) Delhi
B) Western Ghats ✅
C) Rajasthan
D) Indo-Gangetic Plains
Q4. Arrange the following in chronological order:
- IIT-Kanpur Delhi Trials
- First attempt by Tata Group
- Establishment of RCPR Unit
Correct order: 2 → 3 → 1
Q5. Silver Iodide used in cloud seeding is effective because:
A) It evaporates quickly
B) It forms ice-like crystals ✅
C) It absorbs solar radiation
D) It increases wind speed
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