What is “cloud seeding” and what is its relationship to flooding in Dubai?

A torrent of rain on Tuesday (16) flooded parts of Dubai, turned streets into rivers and closed the world's second busiest airport for a while. The deluge of water raised the question: was this disaster caused by the UAE's cloud seeding program?

Officials at the country's National Meteorological Center were quoted as saying that the rain was not caused by this type of cloud seeding. A CNN has contacted the center for comment.

But even if the program had flown its planes through the sky before the storm, it is extremely unlikely that the efforts would have produced more rain than would have fallen naturally.

These understandable attempts to extract more moisture from clouds have existed for decades, but with little evidence of success. But that hasn't stopped some countries, including the UAE, China and the US, from trying to modify the climate.

See below for more information about cloud seeding or propagation:

What is cloud seeding?

Cloud seeding is a weather modification concept that attempts to extract more rain or snow from a cloud than would occur naturally.

Cloud droplets do not form spontaneously. Moisture needs something to condense on – like the water that forms on the side of a cold glass on a hot day. In a cloud, so-called condensation nuclei are tiny particles in the air that moisture can cling to.

Cloud seeding adds more of these particles to the air. Aircraft fly through existing clouds and inject tiny particles, such as silver iodide, with the aim of creating more water droplets or ice.

In any cloud, once enough droplets merge, they become heavy and fall to Earth as rain or snow.

Tiny natural particles, such as dust and dirt, typically serve as the driving force for clouds to condense and release their moisture. Silver iodide can theoretically serve the same purpose.

It works?

It is incredibly difficult to determine what impact – if any – cloud seeding has on precipitation. Experimentation and attempts to quantify its effectiveness have been fraught with challenges.

“How do you know how much precipitation that could actually end up falling from that cloud was due to seeding? Or how much would have fallen without the seeding?” Daniel Swain, a climate scientist at UCLA, previously told CNN . “This is not an environment where you can do a truly controlled experiment.”

Researchers tried. A 2020 study published in the Proceedings of the National Academies of Sciences indicated that a cloud seeding experiment may have produced up to 10% more precipitation than would have fallen naturally. But skepticism still persists in the scientific community.

“There needs to be controlled studies that really show that it was seeding that increased precipitation significantly,” Swain said.

What harm could cloud seeding cause?

As the climate continues to warm due to human-caused climate change, certain parts of the world are becoming hotter and drier. Cloud seeding can be seen as a solution to getting more water to areas that need it, but it can also potentially make other areas drier in the process.

Water – like any other matter – cannot be created or destroyed. It can only be transformed as it moves through the closed loop of the water cycle.

“It's possible that you're actually stealing water from someone else when you do this (cloud seeding), because it can be, at least on a regional basis, a zero-sum game where if water falls from the cloud in one location, it stays even drier when it gets downwind into the next watershed,” Swain said.

An extreme storm system generated torrential rain

The heavy rains that caused unprecedented flooding in the United Arab Emirates, Oman and Iran did not come out of nowhere. They didn't just affect areas that participate in cloud seeding, either.