Clouds do have silver linings

It sounds like the actions of a crazed Bond villain, who is holding the world to ransom by the control and manipulation of the weather.

But the science behind 'cloud-seeding' is very real and has helped the UAE increase its rainfall by 10 per cent, according to scientists.

Cloud seeding involves flying specialised planes and releasing silver iodide pellets into water-laden clouds, boosting the amount of water droplets and precipitating rain.

Increasing the rainfall in the country helps the Emirates to meet growing demand for drinking water, and can decrease its dependency on desalination plants.

However, the process is expensive – costing around Dh5.5 million annually.

"We managed to increase the amount of rain produced by clouds by around 10 per cent," said Omar Ahmed Al Yazeedi, director of research and development at the National Centre of Meteorology and Seismology in Abu Dhabi.

"This has boosted the level of underground water reserves, which was the main objective of the project."

There are no rivers or natural lakes in the UAE, but underground water deposits are found at desert oases at Al Ain and Liwa.

Ocean desalination plants, which convert saltwater to fresh water, are the main source for drinking and agriculture but at the same time are expensive due to the tremendous amount of energy they consume.

The Emirates started cloud seeding in 2000 and now has two aircraft that conduct near daily flights, firing 20 to 30 iodide-filled flares during each sortie, Yazeedi said. Cloud seeding technology has been used by other countries, including China before last year's Olympic Games, with limited amount of success.

Yazeedi accepted there was no scientific measurement to calculate exactly how effective it is.

"But we can see that there are some positive results and in the long run this will help increase our water supply," he said.

The cloud seeding programme takes place in Al Ain, a mountainous area, which has a majority of the country's farmland, east of the capital, Abu Dhabi.

"We can only perform cloud seeding on clouds that already hold water droplets and the best clouds are located in Al Ain," Yazeedi said.

Last year, the UAE undertook 97 flights to enhance rain supply by firing iodide flares on clouds, he added.

"The number of times we seed clouds will increase even more this year since we now own the planes and don't have to lease them," he said.

A study by the Dartmouth College Toxic Metals Research Programme in New Hampshire, United States, in May concluded that excess silver compounds in the air and water could potentially be harmful to humans.

"Prolonged exposure to silver dust or to the silver compounds can result in a permanent blue-gray staining of the eyes, nose, mouth, throat and skin," the study concluded.

Yazeedi downplayed the effects of silver compounds used in the cloud seeding, saying very small amounts of silver compounds were used.

"We follow international standards to avoid having excess silver compounds and so far I don't know of any study that proves it is harmful." (with input from Reuters)

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