Why in News? 

Delhi to Carry Out Five Cloud-Seeding Trials with Expertise from IIT-Kanpur. 

Cloud Seeding 

• It is a weather modification technique used to enhance precipitation by dispersing chemicals like silver iodide, potassium iodide, or dry ice into clouds.  
• These chemicals act as nuclei, aiding in the formation of water droplets and leading to rainfall.  
• The technique helps form ice crystals in clouds, which can generate artificial rain.  
• It is being explored as a possible method to address severe air pollution, especially during high AQI periods. 

Types of Cloud Seeding: 

• Static Cloud Seeding: This involves introducing ice nuclei such as silver iodide or dry ice into cold clouds that contain supercooled liquid droplets. These nuclei stimulate the formation of ice crystals or snowflakes, which grow and fall as precipitation. 
• Dynamic Cloud Seeding: This more complex technique enhances vertical air currents to stimulate rainfall by promoting the formation and growth of rain clouds. It requires a sequence of events to work effectively. 
• Hygroscopic Cloud Seeding: Fine particles of hygroscopic materials, like salts, are sprayed into the base of warm clouds using flares or explosives. These particles act as cloud condensation nuclei, increasing the size and number of cloud droplets, thus enhancing cloud reflectivity and stability. 
• Glaciogenic Cloud Seeding: This method involves dispersing ice nuclei, such as silver iodide or dry ice, into supercooled clouds to trigger ice formation, leading to precipitation. 

Types of Cloud Seeding Techniques 

 Applications of Cloud Seeding: Cloud seeding is used to: 

• Enhance winter snowfall and increase mountain snowpacks, supporting water supplies. 
• Prevent hailstorms and dissipate fog. 
• Induce rainfall in drought-prone areas. 
• Reduce air pollution by enhancing rainfall to clear pollutants from the atmosphere. 

Cloud Seeding