Changing the amount of precipitation that falls from clouds or a ‘weather modification’ is called as cloud seeding. In this process, there are several substances that are dispersed into the clouds so as to facilitate the easy production of the precipitation to provide rainfall in a particular area. In these cases, the microphysical processes are all deliberately modified for the rainfall occurrence. The most important chemicals that are used in his process are silver iodide, solid carbon dioxide which is popularly called as dry ice and also potassium iodide. This procedure can also create the occurrence of snowfall in a region too.Several crystalline structures that resemble the ice like silver iodide will enable the weather modification to produce snowfall. There is a formation of certain ice particles due to the additional foreign substance like silver iodide. When this heavy growth further is not able to hold any longer, it gives away. The precipitation that follows is nothing but the artificial rain or snow. This process is also called as static seeding. There is another process that is called as the dynamic seeding. In this seeding, the ice crystals that are used are nearly 100 times more. This process involves the additional latent due to the addition of substances which after that causes an increase in the buoyancy level and thus causes a rapid growth of precipitation or clouds. This further produces quick rainfall by the dynamic seeding methods. Another method is called as the hygroscopic cloud seeding.In this method, the salts are dispersed to the clouds using flares or other such explosives that force the substances like silver iodide inside the clouds.
The particles are added to the clouds using air-crafts or other such dispersion devices which make the dispersion quite quicker. Or in other cases, there could be even generators that inject these particles into the clouds with the help of devices that are present on the ground. In such cases, the devices like rockets or anti-craft guns are used.
So in short, how does this cloud seeding work?
A seeding agent like silver iodide is initially dispersed into the clouds to form the ice crystal or otherwise, raindrops. This further enhances the precipitation of the clouds and causes the occurrence of cloud or rainfall.
Nowadays cloud seeding is popularly used in areas where the rainfall and snowfall are scanty. Furthermore, the cloud seeding process has indeed become very dependable and low-cost procedure of having a rain shower in dry regions. There have been several uses of cloud seeding. A few examples could surely be cited where cloud seeding has been used. In the case of Beijing Summer Olympics 2008, cloud seeding was particularly used to keep off the rain during the vital opening and closing ceremonies. Thus, clouds seeding have thus proved to be very useful in improvising the occurrence of rainfall in several regions across the globe.
This cloud seeding process sure does have some health effects too. Here are a few.
Silver iodide that is issued in cloud seeding can cause residual injury in human beings. The presence of silver iodide and other substances do not much affect the human healthy or said to have tiny effects on human health. It is also said the exposure to such kind of rain can cause discoloration of hands. The skin could turn an orange or otherwise yellow color. It is also said to leave residue in mucous membranes of human beings. Apart from human begins; there are several other mammals that are equally affected by these issues.
What are the advantages of cloud seeding?
1) Reduces crop damage:
It is a usual thought that cloud seeding being an artificial process of rain may damage the crops. But this is a wrong notion. Cloud seeding does not harm the crops. Instead, it further enhances the crop growth and is also used to suppress hail that is supposedly a reason crops get damaged. Therefore, cloud seeding is very advantageous. Any harmful frozen precipitation is clearly avoided by the occurrence of rainfall due to cloud seeding.
2) Increase of precipitation:
This process increases the hygroscopic particles and thus improvises the rain formation. It causes an easy phase transition of water vapor into liquid water that is nothing but raindrops. In fact, this has seemed to be a clever way to stop drafts too. Excessive precipitation can cause better rainfall and thus, help in the healthy growth of crops. Thus, the overall precipitation improvement is yet another advantageous factor.
3) No droughts:
There are several regions of the world where rainfall occurrences are rare. When the rainfall is quite scanty, there can be cases of droughts too. Thus, cloud seeding has seemed to be a boon in such areas to cause rainfall and help in warding off droughts and famines. Furthermore, this water can be collected in catchments and used later for several purposes. This strategy is well used in areas that suffer from famine.
Cloud seeding does have advantages but at the same time, the disadvantages cannot be completely ignored.
Pollution in clouds: We cannot wholly ignore this. Due to the seeding agents like silver iodide, potassium iodide, etc., there can be cases of pollution occurring in clouds. The dry ice and silver that are injected cause several harmful environmental effects. It increases the silver content of the clouds and may cause some serious impact on the clouds. It is proved that cloud seeding causes only negligible damage to the clouds and thus, can be termed as harmless. Further, the real scare is the use of dry ice or carbon dioxide that is a major concern nowadays because it is a greenhouse gas. Thus, cloud seeding can cause a growing danger called as global warming. Furthermore, it can affect the weather patterns and may eventually cause a serious effect on the habitat of the animals across the globe. Also, it can affect the sea life that can affect the entire food chain. For instance, human beings who feed on the animals may also be affected severely.
Therefore, cloud seeding needs to practice , but in a controlled manner.