Unraveling the Science of Cloud Seeding: Can Humans Truly Control the Weather?


How would it feel if I told you that humans have learned to control the weather to some extent? With the help of cloud seeding technology, we can artificially rain wherever we want. This is a technology that has been used for many years. Countries like China have spent millions of dollars on this technology.

But now, if you want to, you can use it for selfish reasons too. For example, if you are afraid that it may rain on the day of your wedding, a company in France offers cloud seeding services. If you give this company ten million, they will do cloud seeding and ensure that it will not rain on your wedding day. Hearing this, the biggest question you would have right now would be if this technology is indeed so wonderful, the water crisis in our country, there are prolonged droughts in some places, in other places, there may be excess rainfall causing floods, or water shortages, to solve all these problems, why isn’t this technology used? Let us understand the Cloud Seeding technology better. “Have we come to the point where we can control the weather?” “Cloud Seeding is already used in China and Thailand to tackle air pollution.” “This is the result of proper cloud seeding.”

Before understanding cloud seeding technology, we need to understand clouds. What are clouds and how do they form? We all studied in school about three states of matter. Solid, liquid and gas. If we talk about water, the three states of matter of water are Ice, liquid water and gaseous water vapour.

If something is converted from one state to another, that process has a name. When ice turns into water the process is called melting. If water turns into ice, then it is called freezing. If water turns into water vapour, it is evaporation or vaporization. And if water vapour turns back into water, it is known as condensation. It is very basic but remember the word condensation because I will use it a lot throughout the Article.

What happens is that there is a lot of water vapour in the air. If there is a lot of water vapour in the air, then we will say that there is a lot of humidity in the air. Lesser water vapour content means lower humidity. Now, when this water vapour rises in the atmosphere, as you know the higher we go from the ground, with the increase in altitude, the colder it gets. Like, it is very cold in the mountains.

Now, when this water vapour is at a higher altitude, it condenses due to cold. This water vapour turns into water. Extremely small, tiny water droplets. When these water droplets are suspended in the air, we see clouds. Actually, these are clouds. These small water droplets that make up the clouds are minuscule. So small that their diameter is one-hundredth of a millimetre. And there are millions of such droplets in a cloud. If a cloud is at an even higher altitude, the atmosphere is even colder. This means that not only does it condense, but it also freezes. These water droplets turn into tiny crystals of ice and these ice crystals form the clouds. So, in this sense, there are two types of clouds. One is made of water droplets and the other is made of ice crystals. The difference between the two can be easily seen. The ice crystal clouds are at a higher altitude. You cannot see a clear boundary line and they are thinner. The heavy clouds that are closer to the ground are made of water droplets.

Now that we have understood this, the next question is how do these clouds rain? What happens is that these small droplets, when they keep accumulating, more droplets keep joining in, the clouds keep getting bigger, and these small droplets start colliding with each other, they mix with each other and form big droplets. These big droplets go up into the atmosphere and freeze to form ice crystals but the ice crystals also collide into each other to form bigger ice crystals. This process continues until the ice crystals become so big that they start falling on the ground due to their weight. And when this happens, the ice crystals fall on the ground. While falling down, if the temperature of the air is cold, then they will fall like snow, that’s a snowfall. If the air near the ground is warm, the ice crystals will melt and fall like rain droplets. This is how it rains.

Now, if we talk about Cloud Seeding, then in the history of humans, this technology has been introduced by chance, due to an accident. For such accidents, there’s a word in English, Serendipity. It means, by chance, something happens that ends up benefiting us. A big example of a serendipitous discovery is the discovery of a vaccine. When Dr. Alexander Fleming invented penicillin, it was an accident. Cloud Seeding was also a serendipitous discovery.

In 1943, Dr. Vincent Shaefer was an American chemist and meteorologist. He was researching aircraft icing and precipitation. In 1946, he used a cold box for his research. A box that was very cold. While testing something else, during his experiments, he often breathed out in this cold box. As you know, when we breathe out of our mouth it contains water vapour, and if it’s cold outside, it will condense. He noticed this while doing the experiment. You can see this yourself, when you go out in the cold weather and breathe, it feels like you are breathing out smoke or fog. Actually, what you see as smoke or fog are the same tiny water droplets. The water vapour that you breathe out gets condensed into these tiny droplets. Exactly the same process that forms clouds. So it’s not wrong to say that you can blow out a mini cloud during winter. Dr Shaefer also noticed the same thing but he took it one step further. He wondered about what would happen if he cooled the box down further. To do this, he used dry ice. Dry ice is basically a solid form of carbon dioxide. It is commonly used for refrigeration and cooling. And it exists only at a temperature of -78°C. So he placed some dry ice in the cold box. And then when he breathed out into that box, he saw something miraculous. The air that he blew out suddenly turned into millions of microscopic ice crystals. He saw it as a blueish haze. He noticed that if the temperature is reduced suddenly, then the water vapour will instantly turn into ice crystals. This thing happens in clouds at the last stage. When those ice crystals become huge and heavier than the atmosphere. He saw that using dry ice has sped up this process. Dr. Shaefer immediately conducted more experiments to understand what was happening exactly. Finally, when he understood things, he realized that they could be used in real life as well. Why not try to instantly cool the clouds in the sky by using dry ice, so that we can get instant snowfall or rain?

On 13th November 1946, Dr. Shaefer flew a plane from New York. He took 2.5 kg of dry ice with him on this flight and conducted his test on a cloud near Mount Greylock. He literally threw crushed dry ice out of the plane, on top of the clouds, and the result was amazing. He saw instant heavy snowfall and rain. And this was the invention of Cloud Seeding. Today, Dr. Vincent Shaefer is credited for inventing cloud seeding. But before him, there was another man Wilhelm Reich, who claimed to have invented a cloudbuster machine in America. He claimed that by using Orgone energy, cosmic energy, could manipulate the atmosphere and cause rain. He named his research Cosmic Orgone Engineering. But as you can guess, he was a person who made fraudulent claims. His machine didn’t work at all. It was simply a way to steal the credit. Interestingly, there was another scientist apart from Dr. Shaefer who was working on cloud seeding technology but from a completely different perspective. Scientist Dr Berhard Vonnegut. He didn’t want to use dry ice to make the clouds colder for cloud seeding to work. He wanted to use a chemical to carry out the process. His idea was based on the condensation property of water. Something that you may not know is that the process of condensation has a condition. To convert water vapour into water, to undergo the process of condensation, a non-gaseous surface is required. That is, a solid or liquid surface is required to complete the process of condensation. If there is no surface, condensation cannot happen. It is said that without this surface, water vapour will remain as water vapour even if the temperature falls to -10°C. You may say that I claimed earlier in the Article that water vapour condenses when the air cools. How can that happen without any surface? There is a surface, of course. The small dust particles in our atmosphere, the pollens floating around in the air, act like surfaces to carry out the condensation process for clouds to form. The thing is, the better the surface, the faster and better would condensation be. A practical example is in your bathroom. When you take a shower if there are glass surfaces around the shower area, you can see condensation on the glass. The water droplets collect on it. Or when there’s high humidity. You might have noticed that in winter, around the corners of windows, there is a lot of condensation, water droplets form there because there is a lot of humidity inside the house, high water vapour content in the air so, the water vapour condenses when it meets the cold glass on the windows. And that glass provides a surface for the condensation. This was Dr Vonnegut’s logic If a better surface can be provided, the condensation process will be faster. He experimented with chemicals like silver and iodide. Using silver iodide, he found that actually, silver iodide is a good surface for water vapour. Silver iodide has the property to absorb a lot of moisture. So water vapour gets attracted to it and gets converted into water. Today, we know about several materials like silver iodide, which can absorb the moisture around them. We call these materials Cloud Seeds or Cloud Condensation Nuclei. Like Dr. Shaefer threw dry ice on top of the clouds, we can use these cloud seed materials and throw them on the clouds, to speed up the condensation process. So that we get rain. You may think that this is a new technology, but both these methods were already being used by General Electric in 1946. And at that time, it was a revolutionary discovery. For the first time in history, humans were able to control the weather.

After that, the process of cloud seeding gradually improved. First of all, people realized that the method of cloud seeding by using aeroplanes to throw cloud seeds on clouds is very expensive. An alternative to this was to shoot up rockets from the ground that contained cloud seeds so that they could collide with the clouds and scatter the seeds. As soon as the people and governments of the world came to know about this invention, everyone started looking for ways they could use this cloud-seeding technology for their own benefit.

In November 1955, the king of Thailand launched the Thailand Royal Rainmaking Project. He was among the first few people to realize that we can use this technology to counter the effects of drought. In Thailand, farmers were often suffering due to droughts. This method suggested by the king was somewhat successful. Today, this program is run by the Department of Royal Rainmaking and Agriculture Aviation in Thailand. Later, in 2001, the Eureka Organization awarded the king of Thailand for this. In the Indian context, cloud seeding operations were conducted in India in 1983, 1984-1987, and by the Tamil Nadu government during 1993-94. When Tamil Nadu was faced with a severe drought situation. The Karnataka government initiated cloud seeding in 2003-04. In Maharashtra, a US company, Weather Modification Inc. conducted the cloud seeding operations.

However, it is important to note that cloud seeding doesn’t always guarantee rain. There are certain conditions required for cloud seeding to work. First of all, the cloud should have the potential to rain. If a cloud is too high, there will be no use in cloud seeding. Only a cloud that can rain should be chosen. Secondly, the presence of supercooled water is required in the cloud. That is, the water present in the cloud should be in a liquid state even at temperatures below freezing point. Cloud seeding works better in such clouds. Thirdly, there should be enough moisture in the atmosphere. If there’s a lack of moisture in the air, even if you throw a lot of cloud seeds, it will not help. Fourth, the presence of cloud condensation nuclei is necessary. If these nuclei are already present in sufficient amounts, then the cloud will form on its own without cloud seeding. Fifth, wind speed and direction are also important. It is possible that you did cloud seeding, but the wind blew the cloud seeds away from the clouds before they could reach them. It is necessary for the cloud seeds to collide with the clouds. Only then can condensation happen. Sixth, even if all these conditions are fulfilled, rain is not guaranteed. Sometimes the clouds may rain even without cloud seeding.

Cloud seeding is not only used for producing rain but also to clear the air of pollutants. The technology is mainly used to induce rainfall, increase water resources, and reduce the impact of droughts. In the case of air pollution, cloud seeding can help reduce the pollutants in the air by causing them to come down with the rain.

In conclusion, cloud seeding technology has come a long way since its accidental discovery by Dr. Vincent Schaefer. It has found applications in various fields, including agriculture, water resource management, and pollution control. However, it’s important to note that while cloud seeding can be effective under certain conditions, it’s not a guaranteed solution to all weather-related problems. The technology continues to be refined and studied to better understand its potential benefits and limitations.

Thank you for reading!

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