NEWS
02/03/2018 12:42 GMT | Updated 02/03/2018 18:53 GMT

What Is Freezing Rain And Why Is It So Much More Dangerous Than Snow?

It could turn parts of the UK into an 'ice rink.'

Snow-bound Britons have been warned they face a new threat from Storm Emma, with forecasters predicting “freezing rain” will hit parts of the UK.

Freezing rain, which last struck Britain back in 2010, is treacherous for drivers, cyclists and pedestrians as it forms a slippery layer that is often invisible to the naked eye.

The East Midlands, North West England, Wales, the West Midlands and Yorkshire and the Humber are all forecast to be hit by freezing rain from Friday morning until midnight.

What is freezing rain?

Freezing rain, the Met Office explains, is a type of liquid precipitation that falls as a super-cooled water droplet until it strikes a cold surface, at which point it freezes more or less instantly.

Freezing rain tends to start its life as snow, ice, sleet or hail, but passes through a layer of air that’s above 0C on the way down to the ground, melting into a liquid water droplet. If these droplets then fall through a zone of sub-zero air just above the ground, they become super-cooled. When these super-cooled droplets strike surfaces that are close to or below freezing, they freeze on impact forming a glaze of ice.

Why is it worse than snow? 

The glaze of ice formed on impact tends to be clear, making for slippery and dangerous surfaces for pedestrians, motorists, cyclists and anyone else attempting to travel.

The phenomenon is much more common in the US and Canada, where heavy build ups of freezing rain have been known to bring down power lines and trees, though Met Office spokesman Craig Snell tells HuffPost UK it’s unlikely to cause the same damage here. 

The RAC warns that freezing rain has the potential to leave Britain’s roads at their “most treacherous”.

Sara Thornton, of digital weather service Weathertrending, said: “Even if the snow doesn’t get you, gale-force winds and super-cooled freezing rain could turn parts of the UK into an ice rink by the weekend.

“Driving conditions will be positively dangerous, with widespread transport and communication disruption expected. The danger will be greatest in areas that will see warmer air tussling with the big freeze.

“Here we’re likely to see super-chilled water fall as rain, only to freeze instantly as it hits the ground. The result could be an invisible, lethal glaze on roads and pavements that could rank as one of the worst freezing events for many years.”

The Met Office does offer some solace though - freezing rain which falls on top of snow tends to be less lethal. Snell added: “As the snow is soft under the ice, the ice is breaking therefore the effect is not quite as bad as it could have been.” 

Meanwhile if you are faced with this menace, online sources familiar with the phenomenon advise to “walk like a penguin”... or simply play it safe and stay indoors. 

And a lesson in freezing rain from Canada...