How does cloud seeding attempt to increase rain or snowfall?

Cloud seeding is the deliberate introduction of substances into clouds to induce or increase precipitation by acting as condensation nuclei or ice nuclei. The process varies based on the cloud's temperature:1

• Supercooled Clouds: When clouds contain water droplets at temperatures below freezing, they are often seeded with silver iodide or dry ice. These agents provide nuclei that cause water droplets to evaporate and deposit as ice crystals. These crystals then grow rapidly as surrounding droplets attach to them, eventually becoming heavy enough to fall as rain or snow.21
• Warm Clouds: In clouds with temperatures above freezing, substances like sodium chloride or calcium chloride are used. These particles encourage the formation of giant cloud droplets that grow through coalescence, eventually falling as rain.21

While these methods can increase precipitation in specific, localized conditions, the practice is limited in scale and its overall effectiveness remains a subject of scientific debate.31