Cloud seeding is gaining traction in the spotlight as a method to increase rainfall, especially in dry regions. The United Arab Emirates (UAE), situated in one of Earth’s hottest and driest regions, has recently been at the forefront of these efforts. They achieve this by shooting water-attracting salt flares into clouds, combined with releasing salt nanoparticles, a newer technology, to stimulate and accelerate the condensation process. The aim is to create droplets large enough to fall as rain.
Demystifying Cloud Seeding
Cloud seeding is a process involving the dispersion of dry ice, or more commonly, silver iodide aerosols into the upper parts of clouds. This is done to provoke the precipitation process and consequently induce rain. The method uses planes to spray clouds with chemicals, which condense smaller particles into larger rain droplets. Evidence suggests that cloud seeding enhances annual rainfall rates by approximately 10% to 30%. Furthermore, the costs of such operations are significantly lower than those of the desalination process.
Different Approaches to Cloud Seeding
There are several methods used to seed clouds: hygroscopic cloud seeding, static cloud seeding, and dynamic cloud seeding.
Hygroscopic cloud seeding involves dispersing salts through flares or explosives in the lower sections of clouds. These salts grow as water attaches to them. Static cloud seeding entails spreading a chemical like silver iodide into clouds. Silver iodide provides a crystal around which moisture can condense. It makes rain clouds more efficient at dispensing their water, although the moisture is already present in the clouds.
Dynamic cloud seeding aims to enhance vertical air currents, leading to more water traversing the clouds and translating into more rain. This process is considered more complex than static cloud seeding, as it relies on a sequence of events functioning correctly.
Applications of Cloud Seeding
Cloud seeding has diverse applications spanning agriculture, power generation, water pollution control, fog dispersal, hail suppression, cyclone modification, air pollution tackle, and tourism.
In agriculture, it provides relief to drought-stricken areas by creating rain. For instance, ‘Project Varshadhari’ was implemented in Karnataka in 2017. In the power-generation sector, cloud seeding experiments have augmented the production of hydroelectricity over the last 40 years in Tasmania, Australia.
Regarding water pollution control, cloud seeding can help maintain minimum summer flows of rivers and dilute the impact of treated wastewater discharges from municipalities and industries. It has been used for fog dispersal, hail suppression, and cyclone modification, such as with “Project Sky Water” of the U.S.A. in 1962.
Cloud seeding can also potentially be used to settle down toxic air pollutants through the rain and transform typically dry areas into more hospitable locales to enhance tourism.
Challenges involved in Cloud Seeding
However, cloud seeding is not without its challenges. There are concerns about potential side-effects, with the chemicals used possibly being harmful to plants, animals, people, and the environment. Artificial processes could also ultimately alter global climatic patterns, causing traditionally moist places to experience drought.
The process is costly, involving substantial logistic preparation and the delivery of chemicals to the sky. Additionally, as artificial rain falls, seeding agents like silver iodide, dry ice, or salt also descend. Residual silver found near cloud-seeding projects is considered toxic. Dry ice can contribute to global warming, as it consists essentially of carbon dioxide.
Interestingly, some scientists suggest using cirrus cloud thinning techniques and injecting sulphate aerosol into the stratosphere to lessen the adverse effects of global warming. These approaches involve modifying the properties of clouds to allow more heat to escape into space, thereby cooling the planet and reducing global warming effects.
