Could Cloud seeding aid us in combatting drought?

To a certain extent, humans can control the weather. Cloud seeding, often known as artificial rain, is commonly employed nowadays to supply water to drought-stricken areas. However, it has also been abused in the past.

Northern hemisphere countries continue to experience heat waves, wildfires, and catastrophic drought, spurring climate scientists and technologists to experiment with weather modification.

China is presently suffering its longest heat wave on record, with temperatures in the region of Sichuan consistently reaching 40 degrees Celsius (104 degrees Fahrenheit) for the last two months. The heat is driving the Yangtze, Asia's longest river, to reach record lows, triggering a drought that, according to China's Ministry of Water Resources, is "adversely affecting drinking water security of rural people and animals, as well as agricultural development."

In response to the dire situation, the Chinese government has initiated an endeavor to generate rainfall using a process known as "cloud seeding."

The Jialing river has dried up, exposing its river bed in Chongqing, China. Credit: Getty Images

How does it work?

Clouds form as water vapor-containing air rises into the sky, cools, and condenses into ice particles. A cloud arises when enough of the particles cluster together. The frozen particles mix inside the cloud.

When the combined droplets get large and heavy enough, they fall to the earth as rain, snow, or hail, depending on the temperature and other meteorological conditions.

Cloud seeding involves the addition of microscopic particles of silver iodide, a salt with a crystalline structure similar to that of ice, to clouds. This operation can be carried out from a plane or drone, or by shooting particles from the ground.

According to Jose Miguel Vinas, a meteorologist with Meteored, a Spanish firm that operates meteorological websites in various countries, the technology allows water vapor inside clouds to be "tricked" into producing droplets surrounding the silver iodide particles.

When the droplets get heavy enough, a process aided by the addition of silver iodide, they fall from the clouds as precipitation.

The approach explains why Beijing is now having difficulty cloud seeding: There must be at least some clouds in the areas of the sky where rain is desired, and some of China's most water-stressed regions do not have enough cloud cover for the technology to operate. Humans can't make rain clouds out of thin air.

Cloud seeding rockets on the wing of a plane, flying over North Dakota, USA. Credit: Jim Brandenburg; Minden Pictures

History and uses

In the 1940s, scientists at the General Electric Research Laboratory in the United States undertook the first experiments at cloud seeding. The approach is now employed in many nations throughout the world. China is the most recent example, and Beijing has previously used the method to make it rain in advance of the 2008 Summer Olympics.

Russia is also known to use cloud seeding before significant holidays to prevent rain from ruining public celebrations. According to reports, Russia paid 86 million rubles (€1.44 million or $1.43 million) in 2016 for cloud seeding operations to assure a dry May Day celebration. The weather in Moscow was bright on the day of the event.

Today, the approach is largely utilized to make it rain in drought-stricken areas. Aside from China, the United Regions has been practicing cloud seeding, most notably in drought-stricken western states like Idaho and Wyoming.

In the Vietnam War, the US used cloud seeding as a weapon to lengthen the monsoon season, interrupting the Viet Cong's supply chain and slowing its advance by making the land muddy with more rain.

In April 1986, Soviet air force aircraft seeded clouds heading from Chernobyl, where a nuclear power plant had recently detonated, toward Moscow, the Russian capital. The authorities declared the operation a success since the radioactive clouds did not reach Russian cities. Instead, they showered radioactive waste on rural Belarusian districts and the hundreds of thousands of people who lived there.

Controversies

Those last two examples show that technology developed for the greater good can always be misused by people in power. Other variables, though, have some scientists questioning whether cloud seeding is a wise idea.

One argument is that if you seed clouds over your region to prevent droughts, those clouds will not carry rain to the next region, where it would have provided much-needed rain.

Experts also caution that regulating the weather may be too difficult to accomplish and that it may divert attention away from more traditional ways to combat climate change.