Early morning commuters are accustomed to fog blanketing the roads in winter, but those in the aviation game know of something more insidious.
"Freezing fog" occurs when the microscopic water vapours that make up regular fog encounter sub-zero temperatures.
Meteorologist Michael Conway said the "super cooled water droplets" do not transform into ice while airborne, but that changed if they hit something solid.
"It needs a nucleation point. It needs something that the crystal ice solid can actually start forming around," he said.
"So, if you get an aircraft wing or something moving, like the metal fender of a car moving through the freezing fog air, the little super cooled liquid hits the metal and makes it fall into solid ice.
Stuck on the tarmac
Freezing fog is an uncommon "but not unheard of" phenomenon affecting flights in and out of the northern Tasmanian city of Launceston.
Mr Conway said patches were observed on Monday morning amid temperatures as low as -3.8 degrees Celsius.
"You need these days in July with very clear skies, light winds and preferably after rain had happened in the last week or so, that the ground's fairly moist already," he said.
Shannon Wells — who runs the charter airline Par Avion — said planes generally had ice-protection equipment to prevent ice building up mid-flight.
However, Mr Wells said, that protection was typically limited to surfaces exposed during the flight, such as the propeller or leading edge of the wing, similar to how a car has a demister for its windscreen, but little to protect its door handle.
"Those surfaces will get ice on them, it will get heavy and it will cause aerodynamic issues."
Mr Wells said that, in North American and European countries that regularly experience sub-zero winters, aircraft were often bathed in de-icing chemicals before take off.
"But we don't have that in Australia because we're not that cold," he said.
Safety a primary concern
Some light aircraft pilots hold licences that prevent them from flying without a high-level of visibility, which means they are usually grounded whether fog is freezing or not.
However, those who hold licences that allow a greater reliance on an aircraft's instruments can still face trouble in freezing fog.
Civil Aviation Safety Authority's team leader of aviation safety advisors, Michael White, said aircraft can struggle to deliver "the necessary power and lift" because of the increased weight of ice.
He said most pilots facing freezing fog simply had to "wait it out".
"Generally speaking, as the morning progresses, it will burn off with the sun," he said.
Another challenge for aviation
Fog is just one of many challenges that disrupted the normal flow of flights this weekend.
At Launceston Airport, passengers were left waiting for flights as airlines struggled with fog, technical issues and severe storms along the east coast of Australia.
Airport chief executive Shane O'Hare told ABC Radio all these factors had compounded "to make a pretty messy situation".
"Jetstar did cancel a couple of flights on Saturday afternoon in anticipation of fog the following morning," he said.
Fog continued to linger on the airfield on Monday morning. However, Mr O'Hare said, most flights "left pretty well on time".
"So we are operating at the moment but we're holding our breath to see [whether] we can maintain normal operations," he said.
As winter marches on, Mr Conway said Tasmania could experience more freezing fog in the months ahead.
"It looks like things aren't going to be as settled after about Thursday," he said.
"It is another frigid pair of days on the weekend but, apart from that, it's a bit hard to tell when the next big day will be."
