On Tuesday, the United Arab Emirates suffered a year and a half of rain in a single day, leaving much of Dubai under water.
Now, experts have questioned whether the desert city’s sudden deluge could have been caused by weather meddling.
Since the early 1990s, the United Arab Emirates has used a technique called cloud seeding to increase annual rainfall and increase drinking water supplies.
This technique involves launching specialized salt flares from airplanes, before flying into the clouds to cause rain.
So, as Dubai faces its most severe rain ever recorded, MailOnline takes a step-by-step look at how this controversial technique works.
Cloud seeding works by releasing grains of salt or silver iodide into clouds, causing water vapor to condense or freeze into droplets large enough to fall as rain.
Since the early 1990s, the United Arab Emirates has been using this controversial technique to increase rainfall by 15 to 25 percent. Shown here is a United Arab Emirates plane releasing salt flares into a cloud.
Controlling the weather may seem like a futuristic technology, but the principle was actually discovered as early as the 1940s.
General Electric scientists discovered that water cooled to between 14°F (-10°C) and 23°F (-5°C) could not form ice crystals under some laboratory conditions.
Water could not freeze because there was no “core” around which the ice crystal formed.
However, when scientists added silver iodide to water vapor, they discovered that ice crystals formed instantly.
In nature, clouds produce rain or snow when water vapor forms around natural nuclei such as bacteria or dust.
What scientists had discovered was an artificial way of adding nuclei to clouds, which could cause vapor to condense quickly.
Although technology has come a long way, modern cloud seeding uses the same basic ideas that were developed 80 years ago.
UCL hydrology expert Dr Brian Thomas told MailOnline that natural rainfall has four stages.
First, the air cools to the “dew point” as the warm air rises into the cold atmosphere.
Second, water vapor condenses around a “cloud condensation nucleus” (CCN).
Third, those droplets get larger until they are heavy enough to fall.
And finally, the atmosphere “imports” more water into the area to keep the rain flowing.
Dr Thomas said: ‘Cloud seeding acts in step two. The chemicals disperse into the upper atmosphere to act as CCN, thus initiating the rain formation process.’
As long as there is cold moisture vapor in the atmosphere and more moisture continues to be imported, rain will continue.
Not all clouds can be seeded, so the UAE National Meteorological Center maintains a fleet of aircraft (pictured) that can respond when a suitable cloud is detected.
Not all clouds are suitable for seeding, so the NCM has established a sophisticated network of weather stations to monitor atmospheric conditions.
The UAE Rainfall Enhancement Program (UAEREP) said: “The NCM has established a national network of 86 automatic weather stations (AWOS) for weather monitoring, six weather radars covering the entire UAE and one top air station “.
Once the correct type of cloud is detected, specialized seeding aircraft are dispatched to respond.
Mark Newman, deputy chief pilot at NCMS, previously told MailOnline: “As soon as they see some convective cloud formations, they throw us on a flight to investigate.”
Planes are loaded with salt flares that can be burned to cause increased precipitation.
It is estimated that the UAE carries out around 1,000 hours of seeding flights each year, although it is unclear to what extent this actually changes rainfall patterns.
If conditions are believed to be correct, pilots will fire hygroscopic flares that release fine salt dust into the cloud.
While silver iodide is used elsewhere, salt works well in warmer climates and achieves the same effect.
The water vapor then condenses around salt particles and becomes larger and heavier.
Once they reach a certain size, water droplets fall as rain, snow or hail, depending on weather conditions.
The AUE is believed to carry out around 1,000 hours of seeding flights each year to increase rainfall in this way.
In some cases, instead of flying planes into the clouds, seeding can also be done by firing missiles from the ground.
In China, this technique has been used to divert rain from rivers as part of a drought relief effort and reportedly to prevent rain during the 2008 Olympic Games.
In China, missiles containing seeding agents have been fired into clouds as a substitute for seeding aircraft.
On Tuesday, much of Dubai (pictured) was submerged underwater by the worst flooding ever recorded.
Cars swept away and transportation paralyzed as the capital faces a year and a half of rain in 24 hours
Immediately after the flood, questions began to arise about whether cloud seeding had been responsible.
Ahmed Habib, a meteorologist, initially told Bloomberg that at least seven planes took off from Al Ain airport between Sunday and Monday.
However, the NCM quickly denied that cloud seeding operations had taken place before the heavy rains.
Omar AlYazeedi, deputy director general of the NCM, said CNBC that the institution “did not carry out any planting operations during this event.”
Mr. AlYazeedi added: “One of the basic principles of cloud seeding is that you have to target clouds in their early stages before it rains; if there is a severe storm situation, then it is too late to carry out any sowing operation”.
Some have blamed cloud seeding for the increased rainfall, although the NCO denies any seeding has occurred.
Despite the UAE’s frequent use of cloud seeding, some experts still have doubts about whether this could increase rainfall to this extent.
Between Monday morning and the end of Tuesday, Dubai received more than 5.9 inches of rain.
An average year receives 3.73 inches of rain at Dubai International Airport, meaning the country received a year and a half of rain in 24 hours.
The country is one of the driest in the world and receives between 140 and 200 mm of rain per year.
However, during this week’s intense fall, the Emirate of Al Ain received more than 250 mm in one fell swoop.
Studies have suggested that cloud seeding typically increases rainfall by five to 15 percent on average, much less than the extreme deluges seen this week.
Additionally, cloud seeding is typically carried out far from populated areas due to airspace restrictions.
This means it is unclear whether the increase in rainfall over Dubai could have been caused by cloud seeding operations taking place elsewhere.