Cloud Seeding is the mechanism of spreading silver iodide aerosols or more commonly dry ice in the upper portion of the clouds to initiate the precipitation process and form rains. Spreading of silver iodide particles augment the growth of ice particles which result in the formation of rainfall. Seeding normally is performed only on those clouds which show positive results when it comes to the potential of producing rains.
Scientific Mechanism behind Cloud Seeding
By scientific knowledge, we are aware that rainfall occurs after the moisture settles around some of the small particles in the air. A point of saturation is reached when the air can no longer hold the amount of saturation and burst down in the form of rain. Cloud seeding actually helps in providing additional nuclei (such as salts, dry ice, silver iodide, calcium chloride etc) in the air around which the moisture condenses. These types of particles function similar to ice crystals and help in producing rain.
Methods of Cloud seeding
Commonly there are 3 different types of performing cloud seeding which are described as follows:
- Static Cloud Seeding – This is the most basic type of seeding methods in which silver iodide chemical is spread above the rain clouds. These rain clouds already have sufficient amount of moisture in them which essentially condenses around these silver iodide particles. These particles actually make these rain clouds more active and help in forming rain drops.
- Dynamic Cloud Seeding – This is more effective and turbulent form of seeding which accelerates the flow of vertical air currents resulting in more water to pass through the clouds and produce rain. This is a more complex form of cloud seeding than static method and is 100 times more effective than the latter. Researchers have broken down this method into 11 different stages; consequently the method becomes more complex and less dependable.
- Hygroscopic Cloud Seeding – Though this type of seeding has not been fully studied by the scientists, but still it promises more positive results. This method involves dispersing the salt in the lower portion of the rain clouds which becomes larger in size with water and burst out in the form of rain.
All these methods employ the use of airplanes that drop the particles onto the cloud or by using the ground to air rockets or artilleries.
The Challenges behind Cloud Seeding
The process is not free from any controversies and challenges. Many of the scientists believe that the process is too expensive and they should not try interfering with the nature. Others question the validity of the results of the cloud seeding process which is difficult to prove. Some other worry that increasing rain in one area neutralizes with the decreased rain in the other which is becoming the reason of disputes between neighboring states.
However those favoring the process feel that the process has the potential to make up for the delay in monsoon and water loss at various parts of the world.