UAE residents are getting to grips with another sweltering summer – and high levels of humidity are making it feel even hotter.
The Emirates is accustomed to dry heat in July and August, with damp conditions in early June and a notoriously muggy September – often dubbed as Sweat-tember.
But over the past few weeks, the air has been thick with moisture, with no sign of dry conditions.
The mercury has also been on the rise – topping 50°C last week.
Globally, air temperatures soared this month with July 3 recorded as the hottest day the planet has ever seen. Here, we look at why the humidity has stuck this year.
Dr Diana Francis, head of the environmental and geophysical sciences laboratory at Khalifa University in Abu Dhabi, said the heatwave in Europe and soaring humidity in the Middle East all point to the planet heating up.
“Heatwaves in Europe and extreme humidity levels in the Middle East region are linked to a warmer planet with the month of July being the warmest month on Earth since measurements have existed,” she said.
“Global warming is causing the occurrence of heat domes over certain regions – such as the heat dome over Europe during the recent heatwave.
“In July 2023, there have been three heat domes around the globe causing extreme heat and affecting millions of people.”
Climate change, monsoons and heat domes
Dr Ahmed Habib, from the National Centre of Meteorology, said a larger body of humid air over the sea that moved across to the land was one reason for early muggy weather.
“Relative humidity has increased this year,” he said.
“It is because the source of the air mass that affects our country is more, and this moves over the Arabian Sea and the Gulf.
“This air mass is taking in too much humidity from the sea and then moves gradually towards our area so the humidity increases.”
The source of the wind is key to explaining humidity levels. Sea breezes that blow over to the land during the day are humid and drier air is pulled in from the land at night.
Relative humidity shows how close the air is to being saturated.
When temperatures climb, people are left feeling uncomfortable. This is because saturated air cannot easily hold any more water as vapour and cannot effectively evaporate sweat on the skin.
“Relative humidity affects what people feel is the actual temperature, it makes them feel the temperature is rising when the record shows that it is not,” Dr Habib said.
“There is a difference this year because the period of humidity is lasting longer than before.
“The temperature we are recording is the same on average from last year but this year the humid air mass over the sea and the period that the humidity lasts over our area is lasting longer.”
How long will this continue?
Summer humidity in previous years was broken up by a second source of breeze, the air typically drawn in from the desert.
This year, such movement of air is less frequent.
“In summer we are also affected by winds that come from the desert,” Dr Habib said.
“But this year, this source is very low and almost all wind is coming from over the sea, so relative humidity is increasing.
“Before, for example, we may have three or four days of continuous humid mass from the sea, but after that, we also had the dry air mass from the land.
“But this year, the humid air mass lasts for many days. This feeling is lasting longer this month than in other years.”
Conditions in July and August also depend on low-pressure systems caused by the monsoon in Asia.
Meteorologists cannot estimate if the long stretches of humidity will continue.
“It depends on how strong the monsoon is and whether the low pressure affects our country,” he said.
“It’s too early for a forecast.”
Why is this happening?
Dr Francis said global warming was among the reasons the oceans heated up.
“The UAE in particular and the Middle East. in general, are subject to high levels of humidity because they are surrounded by several water bodies which are the main source of humidity in the air – the Red Sea, the Arabian Gulf, the Arabian Sea (and the wider Indian Ocean) and the Mediterranean Sea,” she said.
“During summer, the sun heats the seawater and more evaporation occurs relative to the other seasons.
“While this is a natural phenomenon, its amplitude has been augmented by global warming.
“Our planet is getting warmer and it is known that a warmer atmosphere can hold a larger amount of water vapour than a cold one.
“Additionally, more evaporation is occurring because the oceans and seas are getting warmer due to climate change.”
How dust storms trap heat
The dust load is highest in the atmosphere during summer, according to 2021 research that studied dust activity in the UAE over four decades.
Dr Francis's studies also showed how dust traps heat in the atmosphere.
“We found that the presence of dust in the atmosphere can add up to 6°C to the temperature during the night because of the heat that is trapped in the dust clouds and sent back to the surface at night,” she said.
Dr Francis has led research that highlighted how intensifying “rivers” of water vapour over Africa are the main trigger for dust storms in the UAE and the Middle East during spring and summer.
“We know that under a warmer climate, atmospheric rivers' frequency and intensity increase because of the excess of water vapour that is being put into the atmosphere from evaporation,” Dr Francis said.
“This may lead to additional dust activity.”
