Rainmaking

Rainmaking, often called weather modification in modern usage, refers to efforts to influence precipitation. In traditional cultures, rainmaking included rituals and ceremonies intended to invoke rainfall; today the term generally describes scientific techniques designed to induce or enhance rain, usually through cloud seeding.

Cloud seeding disperses substances into clouds to encourage condensation or ice formation and thus promote precipitation. Agents used include silver iodide, salt, and, in some procedures, dry ice. Delivery methods range from aircraft-based sprayers to ground-based generators and artillery or rockets in older experiments.

Effectiveness is variable and contested. Some controlled studies report modest increases in rainfall under favorable atmospheric conditions, while others find little or no measurable effect. Outcomes depend on cloud type, humidity, updraft strength, wind patterns, and broader weather systems.

Applications include drought relief, water resource management, and wildfire risk reduction, as well as agricultural planning in regions with irregular rainfall. Projects are typically evaluated for cost, potential environmental impact, and transboundary effects when applicable.

Regulation and governance differ by country and region. Many programs require permits, monitoring, and environmental assessments. Internationally, there is no single binding treaty governing civilian rainmaking, though some treaties and norms address environmental modification techniques, particularly in a military context.

Research continues to improve understanding of atmospheric processes and the conditions under which cloud seeding may be advantageous, while also addressing ecological, ethical, and governance considerations.