What is air turbulence?

What is air turbulence?
What is air turbulence?

Atmospheric turbulence, like that which caused the death of a passenger on a Singapore Airlines flight, is a phenomenon that is sometimes difficult to predict and is increasing due to climate change, according to experts.

• Read also: PICTURES | “Severe turbulence”: one dead and several injured during a London-Singapore flight

• Read also: Fatal turbulence in planes: “it’s extremely rare”

Air turbulence is linked to a change in air currents affecting the stability of a flight. They can be caused by thunderstorms, air movements around mountains, cold or warm air fronts, or even jet streams — bands of strong winds circulating around the Earth at certain latitudes.

“Even though meteorologists have excellent tools for predicting turbulence, they are not perfect, and unexpected turbulence can occur,” Thomas Guinn, professor at Embry-Riddle Aeronautical University, told AFP. .

Concerning the flight affected Tuesday, the “first elements seem to indicate turbulence in clear air, the most dangerous type of turbulence,” according to a press release from the Association of Flight Attendants-CWA, representing several tens of thousands of flight attendants. .

This “clear air” turbulence is defined as “sudden and significant turbulence occurring in cloud-free areas and causing violent shaking of the aircraft,” according to the American civil aviation regulator (FAA).

They are “particularly problematic because they are often encountered unexpectedly and frequently without visual cues warning pilots of the danger,” explains the FAA.

According to the agency, this type of turbulence can particularly occur near jet streams and is commonly associated with a wind shear phenomenon (sudden changes in wind speed and/or direction).

Joël Lemay / QMI Agency

According to a 2021 report from the U.S. National Transportation Safety Board, turbulence continues to be “a significant cause of accidents and injuries.”

However, “deaths linked to turbulence on commercial flights are fortunately very rare,” noted Paul Williams, professor of atmospheric sciences at the University of Reading. “As far as I know, there has not been a death linked to turbulence on a commercial flight since 2009,” he added in a statement sent to AFP.

But according to his research, the climate crisis is worsening the frequency of turbulence.

“Climate change is increasing the temperature difference between the cold poles and the hot tropics,” with the latter “warming faster than the poles at cruising altitudes,” explained Paul Williams. “This effect causes more shear in the jet stream, which generates more turbulence.”

According to Paul Williams, severe “clear-air” turbulence in the North Atlantic has already increased by 55% since 1979.

“Our latest projections are a doubling or even tripling of severe turbulence in jet streams in the coming decades, if the climate continues to warm as expected,” he added.

For Thomas Guinn, airplane passengers should therefore keep their seat belts on board as much as possible: “if fastened correctly, there is much less risk of accident.”

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