A few months back, Dubai was in the news for having created artificial rain. In 2011, Prince William and Kate Middleton used some services to keep their wedding dry given the impending perennially rainy English weather. Moreover, in 2008, China also used artificial technology to keep the 2008 Beijing Olympics rain-free. In all these cases, we have talked about playing with the natural rain cycle. But how is this possible? Is there any way to invite rain as per our wishes? Well, cloud seeding has an answer to this.
What is cloud seeding?
Going by the technical definition, cloud seeding is a weather-modification technique that plays a critical role in improving a cloud’s ability to produce rain or snow. The clouds are artificially modified by adding condensation nuclei to the atmosphere. The interaction results in providing a base for the snowflakes or raindrops to form, which eventually fall from the clouds back to the surface of the Earth after enough precipitation has taken place.
Mechanism of causing artificial rain
Most of us have read about the water cycle in our junior classes. We know that at first, the water gets evaporated from the ground and water bodies, then it condenses to form clouds, and finally, it precipitates to fall back on Earth in the form of rain or snow. Each process in this cycle has its intricacies.
As we already know, clouds are made up of water vapors and icy particles. However, the formation of visible and rain-causing clouds is not very simple. When water vapors are not dense enough to fall to the ground as precipitation, they rise high into the sky and become supercooled. Eventually, they condense around tiny particles of dust in the sky, thereby forming a cloud. The tiny particles around which vapors condense are one of the most crucial water cycle components and are known as condensation nuclei.
It takes billions of these condensed water droplets to form a powerful and visible cloud, and this, in turn, requires a large number of condensation nuclei. Now, this is where cloud seeding is playing its role. Technically, cloud seeding works to modify a cloud’s structure to increase its chance of precipitation. And to achieve so, cloud seeding adds small, ice-like particles to clouds, which act as the condensation nuclei, catalyzing the precipitation process.
Usually, silver iodide particles are added artificially to the clouds to act as artificial condensation nuclei. There are different ways to add silver iodide particles to the cloud. Sometimes, large cannons are used to shoot these particles into the sky, and on other days, airplanes drop the particles from above. The super-cooled water vapor molecules in the clouds condense around these particles and then, the condensed water vapor droplets group together. This process continues until the droplets become large enough to fall like rain.
Impacts of cloud seeding
Cloud seeding has been in our society for decades. Most cloud seeding activities primarily aim to respond to cries of water shortages. However, these weather enhancement techniques are sometimes used to clear dense fog by turning it into precipitation. Moreover, this method is also being used by some ski resorts to increase snowfall. Some scientists have also suggested using cloud seeding to get more water from clouds when it does rain, thereby saving that water for times of drought. At present, at least 56 countries have active cloud seeding programs.
I know there are several uses of cloud seeding. But every human invention comes with its risks and cons. And same is the case with cloud seeding. First of all, silver iodide, which is the key ingredient being used in cloud seeding, is toxic to aquatic life. Secondly, there are speculations that enhanced rain in one region can lead to drought-like situations in another region. Moreover, excessive cloud seeding can also induce floods, which is another caused of concern.
However, researchers are aiming to make cloud seeding safer in the coming years. In response to the concerns regarding toxicity, scientists have tested non-toxic replacements for silver iodide. It has been found that calcium chloride is quite effective in this context and low doses of this salt are also unlikely to harm the environment. Moreover, no cases of drought have been reported so far, and even the government is implementing strict measures on the execution of cloud seeding.
Undoubtedly, cloud seeding is a revolutionary technology with a plethora of hidden potential. If used in the right manner, it can prove to be a boon for earthlings!
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Editor at ‘The Secrets Of The Universe’, I have completed my Master’s in Physics from India and I am soon going to join Institute of Space Sciences, Barcelona for my doctoral studies on Exoplanets. I love to write about a plethora of topics concerned with planetary sciences, observational astrophysics, quantum mechanics and atomic physics, along with the advancements taking place in the space industry.