By Maryam Qarehgozlou  

Will cloud seeding cause a blast of moisture in drought-stricken areas? 

December 8, 2018

TEHRAN — Cloud seeding projects are planned to get off the ground in 10 provinces of Iran in a collaborative attempt between the Islamic Revolutionary Guard Corps Aerospace Force (IRGC AF) and the National Cloud Seeding Research Center within the next few weeks.

However, Iran’s Meteorological Organization (IMO) has long been the outspoken opponent of the projects.

IMO has voiced its concerns over the failure of cloud seeding projects warning that such projects are “futile” and “pointless”.

In an interview with Tasnim news agency in January, Hassan Lashkari, a faculty member at the geology department of the Shahid Beheshti University, had explained that managing current water resources as well as application of scientific methods that can enhance clouds’ ability to produce precipitation, also known as cloud seeding, could help in facing the current challenges of water shortage in the country.

Lashkari said that cloud seeding was a viable option that officials should seriously consider noting that in a country like Iran cloud seeding can be very important and with regard to the fact that the country will face severe water shortage in the near future setting up a research center to implement cloud seeding must be high on agenda. 

However, he added, Iran is located in an arid and semi-arid region and any hopes for high precipitation amounts is unrealistic, such climatic condition is the inevitable fate of the country, so that sustainable water management especially in agriculture sector is seriously important.

In April, Amin-Hossein Naqshineh, an expert with the Meteorological Organization, said that employing proper techniques for cloud seeding can yield economic benefits for the country, however, he warned that inappropriate and ineffective measures can result in abnormal precipitation patterns and even flood. 

In August, chief of the Department of Environment Issa Kalantari also said that cloud seeding projects are carried out for propaganda purposes and based on the statements made by IMO they will not affect precipitation levels in the country.  

Kalantari also highlighted that based on the data revealed by IMO cloud seeding projects in Yazd province didn’t increase rainfall in the area at all last year. 

On the other hand, Deputy Energy Minister Rahim Meydani said in January that cloud seeding would increase precipitations by 15 percent which is good for some regions. 

He also stated that while annually 40 billion rials (nearly $1 million) was allocated to cloud seeding projects this year the amount will increase to 90 billion (nearly $2.15 million). 

How does cloud seeding work?

During droughts water shortage strikes but it is possible to make it rain to provide water. Experiments in cloud seeding suggest that it may be possible to artificially create rainfall.

According to physics.org rainfall occurs when super-cooled droplets of water – those that are still liquid but are at a temperature below the usual freezing point of zero centigrade – form ice crystals. Now too heavy to remain suspend in the air, these then fall, often melting on their way down to form rain. Even in dry areas the air usually contains some water. This can be made to come together and form ice crystals by seeding the atmosphere with chemicals such as silver iodide or dry ice.

Nonetheless, it is still hard to tell if the increased precipitation is the result of cloud seeding or it would have rained it the clouds hadn’t been seeded.

Worldwide experience 

Currently, more than 50 countries are reportedly undertaking cloud seeding efforts worldwide.

It was announced in April that China has begun construction of a network of cloud-seeding chambers high on the mountains of Tibet, with the intention of increasing rainfall to the region by an estimated 10 billion cubic meters per year. 

500 of the chambers have been built, burning solid fuel to produce silver iodide particles, which cause clouds to form around them when swept into the atmosphere. However, although researchers tell The South China Morning Post that "data we have collected show very promising results”, it's the first use of cloud seeding technology at this scale and some meteorologists have questioned both its likelihood of success and the potential risks of dramatically increasing rainfall in the target 1.6 million square kilometer region.

The plan, is an extension of a project called Tianhe or 'Sky River' developed by researchers in 2016 at China's Tsinghua University.

However, in an article titled “Scientists throw cold water on Chinese plan to wring precipitation out of the air” published on December 2 in The Globe and Mail, Chinese scientists say it’s far-fetched to think their country can fix a long-standing water shortage by draining the heavens. 

“This is an absurd fantasy project with neither scientific foundation nor technical feasibility,” Lu Hancheng, a scholar at the National University of Defense Technology, wrote as part of a scathing review of the project recently published by ScienceNet, China’s most important hub for scientific discussion.

Other scientists openly criticized the spending of public funds devoted to the project − at least $20-million, and counting. And they questioned whether it was reasonable to imagine that even the best tools of modern science could shape something as complex as meteorological systems.

But Sky River backers are carrying on, preparing for the launch of six monitoring satellites − the first could be in orbit by 2020. In addition, they are working on a program to ground test tools for wringing precipitation from the air.

Additionally in November, it was announced that Delhi's air quality has deteriorated to alarming levels and despite efforts to better it, pollution levels have grown to hazardous and harmful levels. India Today reported the Indian government, after discussing the matter with scientists, has decided to use cloud seeding method to induce artificial rainfall, if the situation worsens, that is if the air quality index reaches 400-500.

The United Arab Emirates, considered a leader in rain enhancement, claims to have witnessed an increase in rainfall of about 10–35 percent following cloud seeding. 

Russia started employ techniques to disperse rain in the 1990s and continues to use it even today. For instance, in 2005, Russian President Vladimir Putin ordered the Russian Air Force to prevent rains over Moscow just before their military parade. In May 2016, the Russian government tried cloud seeding on International Worker's Day to coax the rain clouds to rain elsewhere.

In 2008, China apparently fired a barrage of 1,110 rockets to ensure that the Beijing Olympics opening ceremony was rain-free. Rockets with silver iodide reagents were fired from 21 sites in Beijing to intercept any rain headed towards Beijing and to trigger premature showers.

Big questions remain

Compared to long-term averages Iran’s mean precipitation has doubled over the current water year (September 23 to December 8) with the whole country receiving some 80 millimeters of rain which also quadruples the last year’s average precipitation in the same period. 

Granted precipitation levels increased dramatically this year, but is it going to continue next year? What about provinces with low precipitation levels? For one provinces of Yazd, Isfahan, and Sistan Baluchestan are still fighting drastic and long term draughts. 

But there are still key questions which should be answered like whether or not the projects are cost-effective, or what if the projects fail? Will cloud seeding cause a blast of moisture in drought-stricken areas and bring life back to some dried up wetlands in the country? 

Despite advanced weather modification research since its discovery in the 1940s, scientists are unable to assert even today whether cloud seeding truly brings rain because of the immeasurability of treated clouds and the highly variable dependency of rain on temperature, cloud composition, and other factors. 

Knowledge about crystallization of water in clouds and balance of evaporation and precipitation in the atmosphere too remains limited. Heavy investments in this technology, however, continue.

MQ/MG

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