Cloud Seeding

History

Cloud seeding was discovered after World War II, by Dr. Bernard Vonnegut and his partner Dr. Irving Langmuir. In his experiment Vonnegut noticed that silver iodide (AgI) could turn water vapor into ice crystals. Vonnegut later come to a conclusion that the best way to spread AgI was to mix it with another iodide and then and dissolve the new mixture in acetone he found out that this way one gram of AgI could produce 10^16 nuclei for the ice crystals.

Vonnegut and Langmuir, were not the only scientist to try cloud seeding, he was simply the most successful due to his funding. There were three previously recorded experiments of weather modification in 1924, 1930, and 1932. These experiments were based on the right ideas, however, they simply did not get the sufficient funding. Unlike the previous scientists Vonnegut and Langmuir had General Electric to help them out financially.

Problems and concerns

During the first experiments of cloud seeding significant changes were noted in the amount of precipitation coming out of the seeded area. Upon trying different methods of cloud seeding (i.e. dry ice, AgI) the scientists noticed that more precipitation fell as a result of seeding.

There are still worse concerns since the scientists today lack the knowledge of which rain clouds can potentially escalate into a hail storm, for this reason cloud seeding is dangerous; if the wrong set of rain clouds is seeded the increased precipitation can bring harsher hail, snow, and rain.

Delivery systems

There are many ways to deliver cloud seeding materials (AgI, dry ice, etc.). Most common types are nozzles, which are attached to the plane’s wings. Through these nozzles liquid Carbon dioxide can be sprayed as well as AgI, this is one of the oldest and more reliable ways of delivery.

In this day and age a lot of planes tend to have two racks of flares attached to the bottom of the plane. The racks hold 102 flares each, in these flares are the cloud seeding components. The large number of flares provides for better seeding and higher chances of successful seeding.

There are also ground pumps. These are less effective that air delivery. On ground pumps tend to be inaccurate, although the stations contain some flare racks like on the plane, those racks can only hold about 12 flares. There are still cloud seeding companies that use on ground pumps but air delivery is the preferred way of delivery.

Aircraft specifications

There are many different planes used for cloud seeding. Each of these planes are selected depending on: size of the target, season and temperature, maximum payload (amount of equipment the plane can haul up to the target), maneuverability, speed, and accessibility to spare parts.

These basic guidelines are used to choose the best planes to fly up to the target, or to buy a cloud seeding plane. If the intended target is large in size a large plane will be sent, if the weather above the target is extremely bad then a stronger built airplane will be flown. The more payload the better that means a lot more equipment can be put on board to make sure of a successful seeding. Speed is important because no pilot wants to be inside or above a giant storm for too long. Accessibility to parts simply ensures that the plane will be easy to maintain and thus be more often used than a plane with hard to find spare parts.