Speculation has swirled on social media about whether "cloud seeding" was behind the record rainfall in Dubai which caused flooding and turned airport runways into rivers.
The storm hit the United Arab Emirates (UAE) and Oman this week, killing at least 20 people, and disrupting flights at the world's largest air hub for international travel, trapping hundreds of passengers.
In the UAE's Al Ain city, which borders Oman, a record 254 millimetres of rainfall was recorded — the largest ever in a 24-hour period since records started in 1949.
But what is cloud seeding and is there any truth to the claims of weather manipulation?
What is cloud seeding?
Cloud seeding is a process where small planes fly through clouds and disperse chemicals to increase rainfall in an environment where water scarcity is a concern.
The UAE frequently conducts the process due to the rarity of rainfall, a common feature across the Arabian Peninsula, known for its desert climate where summer air temperatures can soar above 50 degrees Celsius.
Because of this, the region is also known to lack drainage systems to cope with heavy rains and submerged roads are not uncommon during rainfall.
But experts said the storm systems that produced the rain on Tuesday local time were forecast well in advance and that cloud seeding would not have caused such flooding.
Several reports quoted meteorologists at the National Center for Meteorology as saying they flew six or seven cloud-seeding flights before the rains.
Flight-tracking data analysed by AP showed one aircraft affiliated with the UAE's cloud-seeding efforts flew around the country on Monday.
The National, an English-language, state-linked newspaper in Abu Dhabi, quoted an anonymous official at the centre on Wednesday as saying no cloud seeding took place on Tuesday, without acknowledging any earlier flights.
Did cloud seeding contribute?
Jeff Masters, a meteorologist for Yale Climate Connections, said the flooding in Dubai was caused by an unusually strong low-pressure system that drove many rounds of heavy thunderstorms.
"You don't need cloud seeding's influence to account for the record deluge in Dubai," Mr Masters said.
Friederike Otto, a senior lecturer in climate science at Imperial College London, said it was misleading to talk about cloud seeding as the cause of the heavy rainfall.
"Cloud seeding can't create clouds from nothing," she said.
"It encourages water that is already in the sky to condense faster and drop water in certain places.
"So first, you need moisture. Without it, there'd be no clouds."
Meteorologist Maarten Ambaum of the University of Reading in the UK told BBC Newshour the technology just helps "induce those clouds to produce rain rather than just stay nice, fluffy clouds".
He said the rainfall was on a totally different scale to what seeding would produce.
"The amount of material that is being spread in the clouds, and also the area that is being seeded is very small compared to what you would call a significant intervention," he said.
"This system was predicted to produce a lot of rain already, there would be no purpose whatsoever to start seeding operations in this weather system."
He also said the arid land and compact soil mean flash flooding is very likely with a lot of rain.
Climate change a likely factor
The huge rainfall was instead likely due to a normal weather system that was exacerbated by climate change, experts say.
Ms Otto and Gabi Hegerl, a climatologist at Edinburgh University, agree that human-caused climate change makes for a warmer atmosphere that can hold more moisture.
They say this extreme rainfall was likely to become much heavier and worse around the world as the climate continues to warm.
Global warming has resulted in "extraordinarily" warm water in the seas around Dubai, where there is also very warm air above, said Mark Howden, director at the Australian National University's Institute for Climate, Energy & Disaster Solutions.
"This increases both potential evaporation rates and the capacity of the atmosphere to hold that water, allowing bigger dumps of rainfall such as what we have just seen in Dubai," Mr Howden said.
A low-pressure system in the upper atmosphere, coupled with low pressure at the surface had acted like a pressure "squeeze" on the air, according to Esraa Alnaqbi, a senior forecaster at the National Centre of Meteorology.
That squeeze, intensified by the contrast between warmer temperatures at ground level and colder temperatures higher up, created the conditions for the powerful thunderstorm, she said.
The "abnormal phenomenon" was not unexpected in April as when the season changes the pressure changes rapidly, she said, adding that climate change also likely contributed to the storm.
Airport disruptions
Dubai International Airport said after the storm subsided that the heavy rain had caused significant disruptions, with flights delayed and diverted, and advised passengers in Dubai against travelling to the airport.
"We are working hard to recover operations as quickly as possible in very challenging conditions," the airport wrote on X.
"DXB is open but with limited flights departing and arriving. We urge you to NOT come to the airport, unless absolutely necessary."
"Please only come to the airport if your airline has confirmed the departure of your flight."
Some foreign airlines cancelled flights to Dubai.
Paul Griffiths, the airport's CEO, acknowledged continued issues with flooding, saying every place an aircraft could be safely parked was taken. Some aircraft had been diverted to Al Maktoum International Airport at Dubai World Central, the city-state's second airfield.
"It remains an incredibly challenging time. In living memory, I don't think anyone has ever seen conditions like it," Mr Griffiths told the state-owned talk radio station Dubai Eye.
"We are in uncharted territory, but I can assure everyone we are working as hard as we possibly can to make sure our customers and staff are looked after."
The government of Dubai ordered schools to continue teaching classes online on Thursday, as emergency workers cleared debris, including trees and balcony furniture, from the streets.
ABC/wires
