Artificial rain or cloud seeding is a type of weather modification that aims to change the amount or type of precipitation that falls from clouds by dispersing some chemical substances into the air that serve as cloud condensation or ice nuclei, which alter the microphysical processes within the cloud. The most common chemicals used for cloud seeding include silver iodide, potassium iodide and dry ice (solid CO2). The availability of suitable type of clouds is a major challenge for artificial rain. The suitable method for launching the chemicals and the economics of the whole process is also a major challenge. Till now the general approach is that cloud seeding is used only when there is drought in a particular area or there is pollution affecting the quality of life of inhabitants of a city. It will give minimum rainfall in that area so that pollutants will settle down on earth. In other areas it will give minimum potable water so that municipal water demand can be fulfilled.
It is beneficial to use this technique in the areas where there is sufficient average rainfall. If this technique is used for those areas, it will increase the total rainfall in that region. For example, the Malwa region of Madhya Pradesh (Indore, Ujjain, Mandsaur) and Mewar region of Rajasthan (Udiapur, Chittorgarh and Rajsamand) observe average rainfall ranging between 700 and 900 mm per year. There are some major reservoirs in these basins for irrigation and municipal purposes viz., Gandhi Sagar, Rana Pratap Sagar on Chambal River and Bisalpur Dam on Banas River. Due to various regions, some of these reservoirs were not filled up to their full capacity. If by cloud seeding the total rainfall in that region can be increased, it will increase the possibility of increase in water level in the reservoirs and finally the overall water availability in the command area and downstream of the reservoir. This will also increase the water in the lakes and ponds in the major cities and more water for rain water harvesting.
Use of artificial rainfall in the areas of average rainfall as much as in the drought zone and during drought will be instrumental in availing sufficient water for irrigation and municipal purposes.
In 2018,Union minister Mahesh Sharma said that the government should issue a notification to induce artificial rain, in case air quality dips further. “Increasing menace of air pollution is a big concern for a developing country like India. The Centre has decided that if the air quality crosses 500-mark then they will ask authorities to induce artificial rain or cloud seeding over the capital,” he said.
Cloud seeding and Artificial rainwater process
Artificial rainfall is making artificial rain using cloud seeding which changes the properties of clouds. Usually, dry ice, potassium chloride and silver iodide are used. And using airplane, rocket, and power production facilities on the ground they are scattered on the sky.
Rain occurs when supercool drops of water, which are still in liquid form but below freezing point (zero degree Celsius), become ice crystals. These water droplets become too heavy to remain suspended in the air and they fall, melting on their way down and become rain.
What seeding could do is mimic this process and change the amount of precipitation by dispersing substances into the air, which can trigger the process of forming ice crystals by condensing available water in the air. These chemicals may be dispersed either by aircraft or by dispersal devices on the ground.
Whether it is warm or cold, polluted or clean, over a mountain or a city—ultimately, it is the characteristics of the cloud that is key to the success of cloud seeding efforts.
Interest on the subject
According to a 2017 bulletin by the World Meteorological Organisation, “New tools are enabling meteorologists to study and understand clouds and their modification with greater precision than ever, while new technologies such as nanotechnology are expanding possibilities in this field.”
Finding the “right” cloud depends on both temperature and location, the report adds. In ‘cold clouds’ agents such as silver iodide help initiate formation of ice crystals. While in “warm clouds, scientists can use hygroscopic seeding, generally with a simple salt. The salt helps water droplets to collide and produce rain,” the report says. As far as the location is concerned, clouds in tropics are different from clouds in mid-latitudes because temperature influences cloud processes, it says, adding that “different levels of pollution can also develop precipitation differently.”
Over the years, there has been growing evidence that has contested the effectiveness of cloud seeding.
In 2003, the US National Research Council released a report stating that “scientifically acceptable proof for significant seeding effects has not been achieved” although in the past five decades “substantial progress” was made in understanding the natural processes that led to changes in weather.
A 2010 study by the Tel Aviv University’s Department of Geophysics and Planetary Sciences, published in the journal Atmospheric Research looked at over fifty years’ worth of data on cloud seeding, with particular emphasis on the effects of seeding on rainfall amounts in northern Israel. The research concluded that it was changing weather patterns that were responsible for the higher amount of precipitation during these years and not seeding, as was initially thought.
Earlier traces of use
In 2016, 56 countries had cloud seeding operations, compared to 42 in 2011, as estimated by the World Meteorological Association. China had, for the 2008 Beijing Olympics, turned to cloud seeding to try and keep rain away, by inducing rain prior to the games. Most recently, the National Cloud Seeding Research Centre in Iran started its project in the highlands of the central province of Yazd, with other provinces in the pipeline.
In 2015, the UAE launched the Research Programme for Rain Enhancement Science with a budget of US $ 5 million, to advance research and technology of rain enhancement. It has two primary goals: boosting research in rain enhancement globally, and to increase rainfall in UAE and other arid and semi-arid areas of the world.
In this era we have to look out for techniques that would enable the problem of scarcity of water, this process could be a solution to that. This process needs to be followed with correct guidelines.
INFO AND IMAGE- jklu.edu.in, news18.com, thenational.ae/uae/, medium.com