C-141 in the air cloud seeding

Cloud Seeding

Drinkable water has become more scarce as demand and population size has increased.  We must look for other ways to increase rainfall.  Cloud seeding is a means of changing the weather that might help.Cloud seeding enhances a cloud’s ability to produce precipitant through the use of an agent.   The cloud seeding agents are silver iodide, potassium iodide, and dry ice, but recently companies started using table salt.  The two primary methods used are called hygroscopic and glaciogenic seeding.

Seeding Processes

Cloud seeding delivery uses two different methods.  Aerial Cloud seeding uses an aircraft for seeding.  Ariel either delivers the agent to the cloud base or at the cloud top.  Cloud top seeding allows for directGround cloud seeder spraying silver iodide into clouds over mountains injection of the seeding agent into the supercooled cloud top.  Base seeding releases the seeding agent into the updraft of a cloud base.  Ground-based cloud seeding uses dispersion devices located on the ground (generators or canisters fired from anti-aircraft guns or rockets).  Satellites control the ground-based units.

Reasons for seeding

Cloud seeding has three distinct benefits.   Orographic cloud seeding increases snow production in mountainous areas, while the increased snowpack and spring runoff increase the available water supply for cities and hydropower plants.  Convective seeding increases rainfall during the warm seasons.   Agents can equally be used to help reduce hail damage while protecting crop yields, homes, and other property.  The agent causes excess supercooled water to freeze into larger numbers of small particles, rather than much smaller numbers of large particles.   Smaller hail pieces should melt during the transit through the warm sub-cloud layer, or reach the ground as a smaller piece.

Does it work?

Testing results of cloud seeding are lacking.  Companies claim that new research has produced reliable results.  Tests over Texas and New Mexico appear to have increased precipitation amounts.  Generally speaking, this cannot be verified since every storm has different features that produce rainfall amounts.  Companies can be hired to seed clouds. Before the Olympic games in 2008, clouds were seeded to force the rain out before arrival in Beijing.

To save the many do we kill a few?

For years companies relied on silver iodide.  It can cause limited ability or possible injury to humans and mammals with intense or chronic exposure.  Several studies show no negligible environmental or health impacts.  In fact, the silver generated by cloud seeding, which is about one percent of industrial emissions into the atmosphere,  is the equivalent of an individual’s exposure from tooth fillings.  Studies are uncertain in revealing any damage caused by cloud seeding.  To sum up, the question becomes does the benefit outweigh the possible side effects in the future.

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