Jetstar flight fills with 'little clouds' – here's what's happening

It's a familiar site for many Aussies in the Top End, but some were shocked by the scene inside the plane's cabin.

Sudden changes in a plane's cabin could be a bit nerve-racking and the aisle of an aircraft suddenly filling with misty smoke might understandably unsettle some passengers. But for one traveller on a recent Jetstar flight he not only expected its presence but was excited by it.

The passenger snapped a picture from his seat near the back of the plane which showed a mist along the length of the cabin, hanging above travellers' heads and inside open storage compartments clouding visibility.

On the Jetstar flight passengers had a cloudy white mist hang over their heads.
Passengers on the Jetstar flight to Darwin were surrounded by a cloudy mist. Source: Facebook

After sharing the image online many Aussies were alarmed by the sight but the passenger explained it was a common occurrence whenever he flew into Darwin in the Northern Territory — especially at this time of year.

"It's the AC mixing with the Darwin humidity!" he said.

Similar phenomenon to 'seeing your breath'

The sight is caused by the the cool AC inside the plane interacting with the high humidity outside of the cabin, causing "little clouds" to form inside the plane.

"When the hot moist air from outside mixes with the cool air in the plane, it causes condensation," Professor Martin Singh from Monash University told Yahoo News Australia. "This is the same process that causes you to be able to see your breath when it is particularly cold out."

He explained the "key physics" at play, saying the amount of water vapour which is present in the air is "much higher at a higher temperature".

"When moist air cools down, it becomes 'saturated' with water vapour, and any further cooling results in condensation," he said.

Passengers who often fly to humid places in Australia — cities like Darwin and Cairns — said online they frequently experience such mist on arrival.

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