What is Cloud Seeding? Which countries do cloud seeding?

Who knew a hundred years back that rain can be manipulated? There is mythology in various ancient cultures about the rain. There were gods/ goddess associated with it. When they wanted, they could rain?

Today, as per scientific growth and innovative technologies and understanding of the process it is easier to copy the process. Therefore, the process which manipulated the weather to rain is called cloud seeding.

So, Cloud Seeding modifies the amount of precipitation falls from cloud. It does not make or create rain.

 How does Cloud Seeding work?

The first, for cloud seeding the clouds should exist, no matter lesser.

Secondly there are chemicals which are used in cloud seeding are – Silver Iodide, Potassium Iodide and Dry Ice which is solid carbon dioxide.

Some other Chemical like Liquide Propane which expands in to gas has also been used. In some research Table Salt has also been used.

Silver iodide does not work in warm clouds (temperatures above freezing) such as in the tropics. For these clouds, seeding with hygroscopic particles (such as sodium chloride) has been attempted. However, the range of clouds amenable to seeding for precipitation enhancement is actually quite limited. Most clouds that do not produce precipitation naturally are not amenable to seeding to enhance precipitation.

As you might know that the clouds are made up of tiny water droplets or in some cases Ice Crystals when water vapor go up in atmosphere where particles of salt and dust are floating.

These dust and Salt Particles are important in atmosphere which trigger the process of rain.

These water vapours turn into condense water droplets or ice nuclei.

So, During Cloud Seeding the tiny nuclei turn into subfreezing clouds.  Due to Cloud Seeding the snowflakes grow and start falling back to the earth.

 

How to Seed the Cloud?

This can be done through ground-based generators or aircrafts.

So compound Silver Iodide helps in formation of Ice crystal, and one more benefit is that it does not harm humans or wildlife. So, a solution containing a small amount of silver iodide is burned either from ground or released from aircraft and in some cases drones.

When Silver Iodide reaches the cloud it condenses the nuclei.

What are the benefits of Cloud Seeding?

It helps in increasing mountain snowpack which can support the disappearing wildlife at high latitude area.  And, it increases the rainfall as the natural supply for drinking water.

 

How much Effective and successful the cloud seeding is?

The effectiveness of cloud seeding depends upon the project.

However, this has been successful implemented across the globe and it has benefitted the eco system.

For example- Seeding supercooled fog with dry ice (frozen CO2) works very well to clear fog at temperatures below freezing and has been used at airports to improve visibility and allow planes to land or take off.

 

Which of the countries are using Cloud Seeding?

There are many countries across the globe which are practicing cloud seeding.

1-     India – In India cloud seeding operations were done in 1983, 1984, 1987, and 1993- 94 by Tamil Nadu state government due to severe draught.  Karnataka and Maharashtra also did in 2003 and 2004 to tackle the drought.

2-     Indonesia- In Jakarta cloud seeding was used to minimise the flood risk in anticipation of heavy floods in 2013.

3-     Iran – The Country has used to the process to get rain in 10 Iranian Provinces.

4-     Israel- Israel has been enhancing the rain in convective clouds since 1950s. Since 2021 the country has stopped the rain enhancement project.

5-     Kuwait- To counter drought the country has been implementing the could seeding program.

6-     UAE – Cloud Seeding in UAE is a used to address the water challenge in the country. The United Arab Emirates in one of the first country in the Persian Gulf region to use cloud seeding technology.  They use weather radar to continuously monitor the atmosphere of the country.

What are the Impacts of Cloud Seeding on Environment and Health?

The Silver Iodide has health hazard rating of 2, it can cause temporary incapacitation or possible residual injury to humans and other mammals with intense or chronic exposure. However there have been several details ecological studies that showed the negligible environmental and health impacts.

The toxicity of Silver Iodide was extremely low like individual exposure from tooth Filling.

But a 2021 study on aerosol pollution levels across 20 regions of the UAE found higher concentrations of particulate matter (PM)—tiny pollutant droplets that can penetrate deeply into the lungs and cause lung irritation or long-term respiratory illness—in regions that had recently experienced cloud seeding. The researchers attributed regional differences in PM volumes to weather conditions and industrial activity. 

In 2019, the UAE conducted at least 185 cloud-seeding operations, WIRED reported at the time. The end of the year saw “torrential downpours,” and flooding that blocked traffic in streets, neighbourhoods and malls. 

 

History of Cloud Seeding.

In 1891 Louis Gathmann Suggested that shooting liquid Carbon dioxide into rain clouds caused clouds to rain.

Later Bergeron Findeisen process theorised that supercooled water droplets present while ice crystals are released into rain clouds would cause rain.

Scientists have been seeding clouds since 1940s but that time there was no and almost a little proof that the technology had worked. However now the scenario is different.

It all started when in 1940, the world faced the situation of world war 2, and at the same time the atmospheric scientist Bernard Vonnegut discovered that the particles of silver iodide can cause supercool clouds of water vapours to freeze into snow in the lab. However, the technology remained restricted to the military and civilian governments.

But despite the technology decades passed as without knowing that how a cloud evolves after seeding, scientist were also unsure whether silver iodide was doing anything at all.

People are scared of an uncontrolled weather therefore it took some time and experiments to bring this technology to the world.

In 2003, the US National Research Council also released a report which stated that the science was unable to assure that seeding technology had any positive effect. However in 2010, Tel Aviv University study claimed that the silver iodide, and frozen Carbon dioxide seems to have a little impact (if any) on the amount of precipitation.

Research which supported Cloud Seeding

In 2016 Jeff Tilley, the director of weather modification at the Desert Research Institute in Reno, claimed in 2016 that new technology and research has produced reliable results that make cloud seeding a dependable and affordable water supply practice for Many Region.

Ethical Issue against Cloud Seeding

Silver iodide (AgI) is not the only way to seed clouds to enhance precipitation. Nature seeds clouds to enhance precipitation using illite and similar minerals found in dust. These act in a manner very similar to AgI. If nature already does it, one would not consider it unethical or to have any unusual affect on global climate.

However, there are lesser research about the impact on environment.

In the U.S.A, a legal dispute has taken birth over who has rights to water in the cloud- which is ethically disturbing.

Is global warming brought about from cloud seeding?

No. Global warming is brought on by human caused increases in greenhouse gases like CO2, methane, nitrous oxide, and flourinated gases (CFCs, HFCs, etc.). Cloud seeding sometimes causes rain, and is entirely a local effect if it works at all.

 

Cloud seeding is not always successful.

If too many ice crystals are produced as a result of seeding, none will be able to grow large enough to start coalescence. There is, therefore, always a possibility that if cloud seeding is overdone it can prevent a cloud from producing precipitation.

This form of over seeding can be a consequence of excessive air pollution. If over seeded, the growth of large destructive hailstones can be checked. Even if successful, cloud seeding on a large geographical scale may merely redistribute a fixed supply of rain. An increase in precipitation in one area might mean a compensative reduction in another. There are also some problems in cloud seeding—

It does not work in very dry areas where it is most needed because there are rarely any clouds available.