Droughts, arid land, and losing farms have been major concerns for humanity for all of history. Before the industrial revolution, people starved to death if there was a drought season because farms could not grow crops. However, today we have something called “cloud seeding” and as the words suggest, we can sow clouds with seeds that will sprout into rain – another phenomenon we can add to the list of things humans can create.
Cloud seeding has been around since the 1940s but it hasn’t been proven to work since recently. Researchers in Idaho flying two planes have shown that cloud seeding does indeed work by flying through banks of clouds and “sowing seeds” in them. What do they sow the clouds with? Silver Iodide. Particles of Silver Iodide enable water molecules to align themselves into a crystalline structure which means the water molecules freeze. The water particles then get bigger and heavy enough to fall to the ground. A scientific perspective would be to say, Silver Iodide speeds up the process of making rainfall.
photo credit: mother nature network
Another way to sow clouds is to use dry ice. When adding dry ice to the clouds, the water vapour in the cloud would drop to very low temperatures. Ice crystals would form in the process. The ice crystals allow neighboring water vapour molecules to attach and create rain droplets – and ultimately rainfall.
Cloud seeding is not just used for making rainfall. It can also be used to disperse fog, tiny water droplets suspended in air. For example, airports may use salt to seed the clouds. The salt lowers the freezing point of ice and which stops the tiny water droplets from forming. Snowfall can also be created with cloud seeding and some ski-resorts use it during the winter season.
The downside is, cloud seeding isn’t yet perfect. The right conditions of cool moist clouds must be met. And some research shows that cloud seeding only increases rainfall by 15 to 20%. There is also much controversy surrounding seeding clouds, as well as public concern of Silver Iodide, a harmless chemical yet poorly explained to the public. However, many countries are still developing more efficient ways of cloud seeding. And I think we can all agree on the benefits of producing rain and snow especially in times of drought.
