Delhi’s Environment Minister highlighted the importance of collaborating with various agencies to expedite approvals for cloud seeding. 

What is Cloud Seeding?

• Cloud seeding is a technique aimed at artificially inducing rainfall by introducing particles such as silver iodide into clouds.
• These particles serve as nuclei around which moisture can condense, ultimately forming rain droplets.

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How Does It Work?

• Seeding Materials: Common materials include silver iodide, potassium iodide, dry ice, or liquid propane.
• Delivery Method: Seeds can be dispersed using aircraft or ground-based sprayers.
• Condensation Process: The introduced particles encourage the condensation of smaller water droplets into larger ones until they become heavy enough to fall as rain.

Applications and Examples

• India: In Solapur, Maharashtra, cloud seeding reportedly increased rainfall by about 18%.
• UAE: The technique has been employed to enhance rainfall in arid regions.
• China: During the 2008 Beijing Olympics, cloud seeding was used to improve air quality

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Role of Rainfall in cleaning air

• Absorption: As raindrops fall, they absorb pollutants like particulate matter (PM), sulphur oxides (SOx), and nitrogen oxides (NOx).
• Chemical Reactions: When raindrops encounter pollutants, they can undergo chemical reactions that transform these harmful substances into less harmful compounds. 
  • For example, sulphur oxides and nitrogen oxides can react with water and other atmospheric components to form sulfuric and nitric acids.
• Washout: The raindrops, now laden with pollutants or their transformed products, wash these substances to the ground. This process is known as “washout.”
• Scrubbing: As raindrops fall through the atmosphere, they can also scrub the air of pollutants by physically colliding with and removing them. This process is called “scrubbing.”