Cloud Seeding: The Tech Induced rain

Cloud Seeding is relatively old yet not fully exploited means of weather modification.It attempts to change the amount or type of precipitation that falls from clouds,by releasing into the air,substances that serve as cloud condensation.This alters the micro-physical processes within the cloud.The usual intention is to increase precipitation in the area.Other weather modifications are hail and fog suppression are also widely practiced in airports.

Modern cloud seeding started back in the late 1940’s, Owing to a discovery at the General Electric labs in New York in 1946.Vincent Schaefer discovered the principle of cloud seeding in July 1946 through a series of serendipitous events. The discovery led to the realization, through a series of laboratory trials, that flecks of dry ice converted supercooled water droplets (those existing as water at temperatures lower than freezing) to ice crystals . These efforts also demonstrated the ice nucleating properties of various inorganic compounds in certain cold cloud conditions. After many trials,operational and research cloud seeding projects began in the late 1940’s/early 1950’s.

Cloud seeding is no longer considered a developmental project,and is considered a mainstream tool to improve rain precipitation and snow. New technology and research have produced reliable results that make cloud seeding a dependable and affordable water-supply practice for many regions.The most common substances used for cloud seeding include silver iodide and solid carbon dioxide or dry ice. Liquid propane, which expands into a gas, has also been used. This can produce ice crystals at higher temperatures than silver iodide. The use of materials, such as table salt, is becoming more popular after promising research.

Cloud seeding to increase snowfall is done when temperatures within the clouds are between 19 degrees and – 4 degrees Fahrenheit.This is the range at which silver iodide does its best work.Dry ice expansion cools the air to such an extent that ice crystals can nucleate spontaneously from the gas state. Unlike seeding with silver iodide, this spontaneous nucleation does not require any existing droplets or particles because it produces extremely high vapor supersaturation near the seeding substance. However, the existing droplets are needed for the ice crystals to grow into large enough particles to precipitate out.Silver Iodide are produced through the combustion of silver iodide acetone solutions or by burning pyrotechnic flares.Either method produces trillions of microscopic sized particles of silver iodide.Silver iodide increase the probability of ice crystals forming in a cloud at temperatures of approximately -50 C degrees or lower. The dry ice cool the air down so quickly that either unfrozen cloud droplets at temperatures of -50 C or even lower temperatures will quickly freeze or water molecules  become so cold that they freeze and combine together forming very tiny ice crystals.

Cloud Seeding Chemicals are spread by means of aircraft or by dispersion devices located on the ground.For the dispersion of the by  aircraft,the silver iodide flares are ignited and dispersed as the plane flies through the cloud.This leads to the ice nucleation and eventually rain.The release of these materials is also done by the devices on the ground and when released the fine particles are carried up and down by air currents and reach the clouds.On a more advanced front,an electronic mechanism was tested in 2010infrared laser pulses were directed to the air above by researchers from.The scientists inferred that the pulses would encourage atmospheric sulfur dioxide and nitrogen dioxide to form particles that would then act as seeds to naturally promote cloud seeding.A key challenge is in discerning how much precipitation would have occurred had clouds not been seeded and calculate the effectiveness of the cloud seeding project.

The most widely used areas of cloud seeding or its prime targets are the mountain ranges and the farmlands.Experiments in mountain ranges are usually conducted to increase the winter snow-pack which will eventually melt and increase the runoff during the spring season.This gives more water to the crops below and increased productivity from the range land vegetation.Projects conducted in parts which would benefit from the additional precipitation.

There is no evidence that indicate that cloud seeding creates any significant environmental impacts..As noted,questions sometimes arise regarding the environmental effects of silver iodide used in cloud seeding, which include silver iodide aerosol complexes such as silver iodide-silver chloride. Silver iodide is the primary component of silver iodide-based ice-nucleating complexes used in cloud seeding, and all these complexes will be referred to as silver iodide .Measurements made since the 1950’s infer that the amount of silver iodide deposited in the area after a long standing cloud seeding project falls several orders of magnitude short of the amount known to be toxic to living organisms.  It is often difficult to detect any silver accumulation above the background amounts already present in the environment.

Although we practice various methods of weather modification such as cloud seeding etc.We come to ask ourselves if we are technologically advanced to modify forces of nature that are not in our control.Nevertheless this is undeniably an effective technique to getting better rain in targeted areas and requires more extensive research to maximize the effectiveness and be environmentally friendly at same time.


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