Cloud seeding is a weather-modification technique that enhances natural rain through the addition of particulates to clouds. Silver iodide, dry ice, and potassium iodide are the most commonly used particulates in cloud seeding. These small particles are called condensation nuclei once they are suspended in the atmosphere.
What is Precipitation?
Precipitation refers to water (frozen or liquid) that falls from the atmosphere to the earth’s surface. This often occurs in the form of rain, snow, or hail.
How Rain Occurs
When water evaporates into the atmosphere, it cools to form tiny water crystals through a process called condensation.
The water crystals need particles on which they can stick to form larger water droplets.
Condensation nuclei such as silver iodide allow several water crystals to combine, thereby forming large water droplets.
Without condensation nuclei, the water crystals in the atmosphere cannot form water droplets.
When the water droplets become heavy, they fall back to the ground as rain or snow.
HOW DOES CLOUD SEEDING WORK?
Cloud seeding technology allows humans to manipulate the structure of clouds by adding condensation nuclei into the clouds.
By employing the cloud seeding technique, scientists can modify the weather accordingly. Cloud seeding is also called rainmaking.
A scientist who studies weather and other atmospheric phenomena is called a meteorologist.
Meteorologists often use drones, rockets, and rain dispersal aircraft to introduce tiny solid particles into the atmosphere. Ground-based canons and generators can also be used to shoot condensation nuclei into the atmosphere.
The water crystals forming clouds are highly attracted to these solid particles because they have a similar structure.
Once attached to the condensation nuclei, the water crystals become dense. This causes gravity to pull them back to the surface of the earth.
Cloud seeding thus increases the chances of precipitation.
CLOUD SEEDING METHODS
Clouds can be seeded using three methods:
Static Cloud Seeding
The static seeding method involves the addition of chemical compounds such as silver iodide onto clouds.
Since silver iodide particles have an ice-like structure, the water crystals can easily cling onto the particles. This process makes rain clouds more effective when it comes to dispensing water.
The static cloud seeding technique is one of the commonly used methods.
Dynamic Cloud Seeding
The dynamic cloud seeding technique requires more silver iodide than the static method.
It greatly enhances the movement of vertical air currents in the clouds. This, in turn, causes more water crystals to stick onto the silver iodide particles.
This method is, however, not as reliable compared to static cloud seeding since it relies on a series of events.
Hygroscopic Cloud Seeding
In this method, scientists spread hygroscopic salts onto rain clouds. A hygroscopic salt is any type of salt that can absorb moisture from the atmosphere. Sodium chloride is a good example of a hygroscopic salt.
As the salt crystals take in more water, they increase in size and also become heavier. Consequently, they will fall back to the ground as precipitation.
The salt particles can be added into clouds through specialized explosive devices and flares attached to aircraft wings.
HISTORY OF CLOUD SEEDING
Experiments on cloud seeding were first done in 1946 by an American meteorologist and chemist called Vincent Joseph Schaefer.
Vincent J. Schaefer seeded clouds by dropping dry ice (solid carbon dioxide) onto clouds. This led to the formation of human-made snow.
The use of silver iodide in cloud seeding was introduced by Bernard Vonnegut, an American atmospheric scientist.
Cloud seeding became popular over the years and was even used by the United States during the Vietnam War.
Currently, countries around the world use different cloud seeding methods to create precipitation.
ADVANTAGES OF CLOUD SEEDING
Creates More Rain
-The primary reason for seeding clouds is to create rain. As such, this rainmaking technique can help stimulate rain clouds to produce more rain.
-Rain improves crop productivity and can also increase vegetation cover in an area.
-This method can improve rainfall quantity in areas with minimal rainfall.
Cloud Seeding Can Regulate Atmospheric Conditions
-Cloud seeding has been used in different parts of the United States to modify weather conditions.
-For example, scientists are now able to reduce the size of hailstones during thunderstorms to prevent the destruction of property.
-Some countries also use this technique to prevent the formation of fog, thereby preventing aviation accidents. Cloud seeding has also been used to prevent flooding in countries such as Indonesia.
Reduces The Impact of Drought
-Through cloud seeding, meteorologists can mitigate the effects of drought by enhancing rain in drought-prone areas.
-The United Arab Emirates (UAE) and other countries have greatly benefited from cloud seeding.
-Scientific data shows that cloud seeding can increase rainfall by up to 35%. However, this may vary depending on the atmospheric conditions.
DISADVANTAGES OF CLOUD SEEDING
Cloud Seeding is Potentially Harmful to The Environment
-Some of the chemical compounds used in cloud seeding can impact various aspects of the environment.
-For example, silver iodide can affect human health and may also alter marine ecosystems. As such, meteorologists are working on finding eco-friendly condensation nuclei.
-Seeding clouds is quite costly. A lot of resources are needed to formulate the chemicals used in cloud injection.
-Additionally, the procedures associated with this process are equally costly.
Cloud Seeding Cannot Work In The Absence of Clouds
-Cloud Seeding technology does not lead to the formation of clouds. Instead, the particulates introduced into the atmosphere cling to the already existing water crystals.
-This means the technique cannot work when there are no clouds in the atmosphere.
Unpredictable Weather Patterns
-Many experts warn that cloud seeding could cause severe changes in weather patterns.
-Areas that often receive minimal rain are likely to get flooded if cloud seeding is not done correctly.
CLOUD SEEDING HAS A LOT OF POTENTIAL
Seeding clouds using silver iodide, potassium iodide, and solid carbon dioxide can improve precipitation. This technique has allowed scientists to control weather conditions in different regions.
Nonetheless, some of the chemical substances used during the cloud seeding process are not good for the environment. A lot of research needs to be done to make cloud seeding foolproof.