Last year, the National Centre of Meteorology (NCM) ran no fewer than 242 missions. Courtesy National Centre for Meteorology
Last year, the National Centre of Meteorology (NCM) ran no fewer than 242 missions. Courtesy National Centre for Meteorology
Last year, the National Centre of Meteorology (NCM) ran no fewer than 242 missions. Courtesy National Centre for Meteorology
Last year, the National Centre of Meteorology (NCM) ran no fewer than 242 missions. Courtesy National Centre for Meteorology

Is there a way to make cloud seeding more effective?


Daniel Bardsley
  • English
  • Arabic

It is around two decades since cloud seeding began in the UAE, and this technique to promote precipitation is now as popular as ever.

Last year, the National Centre of Meteorology (NCM) ran no fewer than 242 missions.

Cloud seeding is used in many other countries, among them the United States, where pioneering research was carried out in the middle of the 20th century.

Much of the work then involved injecting thousands of tiny silver iodide particles into the atmosphere, often by using a plane loaded with flares. These particles mimic the actions of ice nuclei – particles around which ice crystals form – and so promote precipitation, which might fall as snowflakes or rain.

Stan Cooper / The National
Stan Cooper / The National

Silver iodide is still commonly used in colder conditions, while in warmer temperatures, salt (sodium chloride) particles are often preferred.

Over the years there has been little change in the particles used and the efficiency of cloud seeding has not shown significant improvement.

While some researchers remain unsure whether cloud seeding works at all, in hazy conditions there is likely to be a 10 to 15 per cent increase in the rainfall generated by a cloud, according to NCM figures, while in clearer conditions the increase is about 35 per cent.

___________

Read more

Water scarcity in sharp focus as Abu Dhabi hosts rain enhancement prize

UAE seeding flights 'boost rainfall from clouds by a third'

Heads in the clouds: how the UAE hopes to make rain for the good of the world

___________

Attempts have been made to mix salt with other substances, including other salts and polymers that also attract water, to increase effectiveness. However, improvements have been modest.

And there are many challenges linked to cloud seeding aside from what particles are used. Professor Ken Carslaw, a professor of atmospheric science at the University of Leeds in the United Kingdom, said there is also the issue of when and where in a cloud the seeding is carried out.

“You have to seed in the right place and the right time. If not, you get even the opposite effect from what’s intended,” said Prof Carslaw, who researches how particles in the atmosphere behave and what effect they have on clouds.

“In some cloud systems, you can get fairly predictable results, but that’s not the case in all situations … Our ability to measure the cloud and understand how it will respond is incomplete; that makes cloud seeding unpredictable. We don’t even know how a cloud will evolve naturally.”

Although there is much about cloud seeding that remains to be learnt, recent work at Abu Dhabi’s Masdar Institute, part of Khalifa University of Science and Technology, could lead to a step change in the efficiency of cloud seeding. This is especially in cases where salt particles are used.

Last year, as was reported, Professor Linda Zou, a professor of chemical and environmental engineering at the university, applied for a patent for the use of a titanium dioxide coating on salt particles.

Linda Zou, a professor of chemical and environmental engineering with novel cloud seeding materials at the Masdar Institute. Chris Whiteoak / The National
Linda Zou, a professor of chemical and environmental engineering with novel cloud seeding materials at the Masdar Institute. Chris Whiteoak / The National

Now, in a paper in the journal American Chemical Society (ACS) Nano, Prof Zou and her co-researchers have published full details of how they have used nanotechnology – science at the nano scale – to produce these particles, and how much more effective they appear to be at adsorbing water vapour than pure salt (adsorption – not to be confused with absorption – involves the adhesion of the water molecules to the particles).

High levels of water vapour adsorption are essential if particles are to successfully seed clouds, but on their own, without a coating, salt particles only work at very high humidity conditions and tend to be ineffective when relative humidity is less than 75 per cent.

Linda Zou, a professor of chemical and environmental engineering with novel cloud seeding materials at the Masdar Institute. Chris Whiteoak / The National
Linda Zou, a professor of chemical and environmental engineering with novel cloud seeding materials at the Masdar Institute. Chris Whiteoak / The National

The research involved tests in a cloud chamber, which is a three-dimensional environment in which condensation and water droplet formation caused by the seeding material can be assessed. While Prof Zou cautioned that this is very different from an actual cloud seeding operation, she nonetheless described the results as “very positive and promising”.

A key characteristic is the way in which the titanium dioxide coating or shell, and the salt particle that it surrounds, act in synergy with one another to adsorb more water vapour, which turns into larger droplets.

The titanium dioxide shell is a hydrophilic (water-loving) surface, and when it adsorbs water vapour it increases the relative humidity around the salt particle, and this can be turned into drops of liquid.

As a result of this synergistic effect, in the cloud chamber experiments, this structure absorbed many times as much water vapour as pure sodium chloride. Also, water turned to liquid at a much lower relative humidity than when normal salt particles were used. Thirdly, the new particles created much larger water droplets. Prof Zou is not surprised at the positive findings.

“I designed that [particle] because I expected the nanostructure would enhance the function, but I am glad to see such significant and very positive improvement,” she said.

“We found the total numbers of large water droplets that are likely to form rainfall have increased 290 per cent.”

The larger water droplets formed by the new nanostructured particles are, said Prof Zou, more likely to accelerate droplet growth and trigger rainfall.

Numerical modelling is being carried out to predict how effective the particles will be in atmospheric conditions, and it will also be crucial to see if the lab results can be replicated in actual cloud seeding operations. Field trials have yet to happen, but planning and preparation is being carried out by the National Centre of Meteorology.

“We cannot tell the time [when trials will happen] … but we’re in the process of planning for the field trials,” said Prof Zou, whose project is financially supported by the UAE Research Programme for Rain Enhancement Science.

“We are now addressing the challeng of the scale-up, [to produce the particles in] larger quantity.”

So, after many years in which cloud seeding operations have not shown significant progress in efficiency, the new capabilities of scientists to operate at the nano-assisted level could provide a much sought after breakthrough.

– The study’s other authors are Dr Yanlong Tai, Haoran Liang (a PhD student), Dr Nabil El Hadri, Dr Steve Griffiths and Dr Mustapha Jouiad of Khalifa University, and Dr Ali Abshaev and Dr Buzgigit Huchinaev of the High-Mountain Geophysical Institute in Russia.

Global state-owned investor ranking by size

1.

United States

2.

China

3.

UAE

4.

Japan

5

Norway

6.

Canada

7.

Singapore

8.

Australia

9.

Saudi Arabia

10.

South Korea

The biog

Name: James Mullan

Nationality: Irish

Family: Wife, Pom; and daughters Kate, 18, and Ciara, 13, who attend Jumeirah English Speaking School (JESS)

Favourite book or author: “That’s a really difficult question. I’m a big fan of Donna Tartt, The Secret History. I’d recommend that, go and have a read of that.”

Dream: “It would be to continue to have fun and to work with really interesting people, which I have been very fortunate to do for a lot of my life. I just enjoy working with very smart, fun people.”

Frankenstein in Baghdad
Ahmed Saadawi
​​​​​​​Penguin Press

Key facilities
  • Olympic-size swimming pool with a split bulkhead for multi-use configurations, including water polo and 50m/25m training lanes
  • Premier League-standard football pitch
  • 400m Olympic running track
  • NBA-spec basketball court with auditorium
  • 600-seat auditorium
  • Spaces for historical and cultural exploration
  • An elevated football field that doubles as a helipad
  • Specialist robotics and science laboratories
  • AR and VR-enabled learning centres
  • Disruption Lab and Research Centre for developing entrepreneurial skills
Lexus LX700h specs

Engine: 3.4-litre twin-turbo V6 plus supplementary electric motor

Power: 464hp at 5,200rpm

Torque: 790Nm from 2,000-3,600rpm

Transmission: 10-speed auto

Fuel consumption: 11.7L/100km

On sale: Now

Price: From Dh590,000

Sinopharm vaccine explained

The Sinopharm vaccine was created using techniques that have been around for decades. 

“This is an inactivated vaccine. Simply what it means is that the virus is taken, cultured and inactivated," said Dr Nawal Al Kaabi, chair of the UAE's National Covid-19 Clinical Management Committee.

"What is left is a skeleton of the virus so it looks like a virus, but it is not live."

This is then injected into the body.

"The body will recognise it and form antibodies but because it is inactive, we will need more than one dose. The body will not develop immunity with one dose," she said.

"You have to be exposed more than one time to what we call the antigen."

The vaccine should offer protection for at least months, but no one knows how long beyond that.

Dr Al Kaabi said early vaccine volunteers in China were given shots last spring and still have antibodies today.

“Since it is inactivated, it will not last forever," she said.

'Nightmare Alley'

Director:Guillermo del Toro

Stars:Bradley Cooper, Cate Blanchett, Rooney Mara

Rating: 3/5

F1 The Movie

Starring: Brad Pitt, Damson Idris, Kerry Condon, Javier Bardem

Director: Joseph Kosinski

Rating: 4/5

The specs

Engine: 2.0-litre 4cyl turbo

Power: 261hp at 5,500rpm

Torque: 405Nm at 1,750-3,500rpm

Transmission: 9-speed auto

Fuel consumption: 6.9L/100km

On sale: Now

Price: From Dh117,059

TRAP

Starring: Josh Hartnett, Saleka Shyamalan, Ariel Donaghue

Director: M Night Shyamalan

Rating: 3/5

How green is the expo nursery?

Some 400,000 shrubs and 13,000 trees in the on-site nursery

An additional 450,000 shrubs and 4,000 trees to be delivered in the months leading up to the expo

Ghaf, date palm, acacia arabica, acacia tortilis, vitex or sage, techoma and the salvadora are just some heat tolerant native plants in the nursery

Approximately 340 species of shrubs and trees selected for diverse landscape

The nursery team works exclusively with organic fertilisers and pesticides

All shrubs and trees supplied by Dubai Municipality

Most sourced from farms, nurseries across the country

Plants and trees are re-potted when they arrive at nursery to give them room to grow

Some mature trees are in open areas or planted within the expo site

Green waste is recycled as compost

Treated sewage effluent supplied by Dubai Municipality is used to meet the majority of the nursery’s irrigation needs

Construction workforce peaked at 40,000 workers

About 65,000 people have signed up to volunteer

Main themes of expo is  ‘Connecting Minds, Creating the Future’ and three subthemes of opportunity, mobility and sustainability.

Expo 2020 Dubai to open in October 2020 and run for six months

Three tips from La Perle's performers

1 The kind of water athletes drink is important. Gwilym Hooson, a 28-year-old British performer who is currently recovering from knee surgery, found that out when the company was still in Studio City, training for 12 hours a day. “The physio team was like: ‘Why is everyone getting cramps?’ And then they realised we had to add salt and sugar to the water,” he says.

2 A little chocolate is a good thing. “It’s emergency energy,” says Craig Paul Smith, La Perle’s head coach and former Cirque du Soleil performer, gesturing to an almost-empty open box of mini chocolate bars on his desk backstage.

3 Take chances, says Young, who has worked all over the world, including most recently at Dragone’s show in China. “Every time we go out of our comfort zone, we learn a lot about ourselves,” she says.

Infiniti QX80 specs

Engine: twin-turbocharged 3.5-liter V6

Power: 450hp

Torque: 700Nm

Price: From Dh450,000, Autograph model from Dh510,000

Available: Now

THE%20SPECS
%3Cp%3EBattery%3A%2060kW%20lithium-ion%20phosphate%3Cbr%3EPower%3A%20Up%20to%20201bhp%3Cbr%3E0%20to%20100kph%3A%207.3%20seconds%3Cbr%3ERange%3A%20418km%3Cbr%3EPrice%3A%20From%20Dh149%2C900%3Cbr%3EAvailable%3A%20Now%3C%2Fp%3E%0A
UPI facts

More than 2.2 million Indian tourists arrived in UAE in 2023
More than 3.5 million Indians reside in UAE
Indian tourists can make purchases in UAE using rupee accounts in India through QR-code-based UPI real-time payment systems
Indian residents in UAE can use their non-resident NRO and NRE accounts held in Indian banks linked to a UAE mobile number for UPI transactions