Abu Dhabi, UAEMonday 6 July 2020

Environment

Cloud seeding: Blue sky thinking to help scientists make it rain during UAE summer

Academics repeatedly flew a jet into clouds in the height of the country's summer to find out more about them

More rain could fall in the Emirates in future summers as a result of a research project which has led to a greater understanding of UAE clouds.

Last August, scientists flew a Learjet over the country on 12 separate missions to boost their knowledge of the make-up of clouds which form during this time of the year and gain insights into how they could be better manipulated to make more water fall.

The bulk of the country's rainfall generally occurs from November to April, with only a meagre amount of rain recorded from May to September.

There is the potential here, I think, really to enhance rainfall

Roelof Bruintjes

The results could lead to changes in the country’s cloud seeding programme and more experiments this year, after readings uncovered “unique” formations that had developed due to the region’s climate, dusty landscape and proximity to water.

“Nature produces something, and we are trying to modify it,” Roelof Bruintjes, a researcher who worked on the project, said. “But we need to know what are we trying to modify.

“So we took a lot of measurements of the clouds, to find out how does precipitation form in the cloud, what is the evolution, how efficient are the clouds in terms of producing precipitation and what is happening in these clouds? How do they grow?

“We found there are certain things here that are unique in the world. We have found another data point globally that is not consistent with continental clouds or maritime clouds, it is somewhere in between. You get large [water] particles, but you don’t get an efficient process to transfer the water to the ground.”

Among the theories arising from the research is that the location which clouds were seeded at could be changed to maximise rainfall, while the importance of medium-sized droplets may have been overlooked.

“We are looking at what droplet sizes we need to create in a cloud to really get more of the water down to the surface,” Dr Bruintjes said.

“Secondly, we’ve always been thinking of seeding at the cloud base, but maybe there is also an opportunity to have an enhancement effect if we seed at mid-levels. The measurements suggest we really need to look at this, we can do this in the modelling and some experimentation.

“We are now starting to put a picture together. There is the potential here, I think, really to enhance rainfall but we may have to adapt some of our methods to make it more efficient.”

On the second day of the International Rain Enhancement Forum in Abu Dhabi, delegates were also told about efforts to develop a new material that could be used for cloud seeding, in addition to salt particles, dry ice and chemicals such as silver iodide which are used currently.

Research is also ongoing to improve the delivery method into clouds, after research found that some spring-loaded flares did not ignite properly, while in others material was still clogged inside after firing. A new method where cloud seeding materials would be sprayed from pressurised canisters has been tested.

Updated: January 21, 2020 09:34 AM

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