Cloud Seeding: The Pros and Cons of Weather Modification

Pros and cons of cloud seeding
Many are not aware of cloud seeding, a technique that enables the production of rain or snow. This post provides some information about the same and also enlists its pros and cons.
It's Raining!
In spite of doubts arising about the effectiveness of the cloud seeding technique, it is believed that China spends $60 to $90 million a year, adding to the amount spent from 1995 to 2003 ($266 million) on it, with an aim to produce about 1.7 trillion cubic feet of rain a year.
Cloud seeding can be referred to as a weather modification process that helps in producing or inducing precipitation (rain or snow). This technique is more commonly used to induce artificial rain. This process involves the dispersal of chemicals (such as silver iodide, etc.) over the clouds that act as stimulants for precipitation to occur. What happens is, these particles act as nuclei for condensation of water droplets or as nuclei for crystallization of snow particles, depending upon the temperature conditions within the clouds. The dispersal of the particles may be done by an aircraft, a rocket, or even a ground seeding generator (or dispenser). When a dispenser is used for seeding, the chemical that is used is sprayed across a propane flame. The chemicals that can be used in this technique are dry ice (solid CO2), silver iodide, potassium iodide, liquid propane, table salt, etc.

Mostly, silver iodide and dry ice are used in "cold rain" cloud seeding to induce snow and hygroscopic substances, while salt is used in "warm rain" cloud seeding to induce rain.

Here is a pictorial representation of the process. In this case, the process shows the production of rain.
Cloud Seeding Process
Cloud seeding process
This process has many advantages, is quite popular, and is being used widely in many places around the world; however, there are also some disadvantages associated with the same.
• This technique has proved beneficial in areas where there is water scarcity, i.e., where water is needed. Thus, areas affected by droughts are benefited to a great extent.

• It prevents the damage of crops in certain areas that occurs due to less rainfall conditions and also makes possible the growth of food crops in many other areas. As a result, severe and problematic conditions such as famine can be avoided due to increase in the amount of rainfall.
• It can be used to suppress the unfavorable conditions such as fog and hail in airports. Suppressing such unfavorable conditions can also prevent crop damage in many areas.

• This technique may promote tourism by making the weather conditions in some typically dry areas more favorable for tourists, thus, also contributing to its economy.
• This technique makes use of chemicals such as silver iodide, potassium iodide, etc., whose long-term effects are still being assessed. That is, how far these chemicals are safe and may not pose a threat to the health of plants, animals, even humans, and the environment is not yet known.

• As it involves the dispersal of chemicals over the clouds, these chemicals would have to be transported there, which is usually done using an aircraft or rocket, which is why the process is expensive.
• In some cases, managing the amount of rain may become a problem that may further lead to flooding in certain areas.

• The use of dry ice or solid CO2 though not often, is believed to contribute to global warming. This is because CO2 is a major greenhouse gas.
• It is also believed that though this process causes an increase in precipitation in certain areas, it may lead to an alteration in the weather patterns of other neighboring areas; in some cases, even depriving the other areas of precipitation. Research studies also reveal that this alteration in weather pattern may also have a negative effect on the marine life in certain areas, which, in turn, affects the people who are dependent on them for food.

• There are still doubts about the effectiveness of this technique, i.e., whether the process has caused the rain or it would have rained anyway otherwise. This is because the chemicals are dispersed usually on rain-bearing clouds. Moreover, clouds are a must, and this process may not be of any use in completely dry regions.
Cloud seeding as a process is, indeed, a great advancement in technology considering the pros. However, considering the cons, we understand that improvements are yet to be made for the enhancement of this technology.