LONDON (CNN) - Another night of frigid temperatures and heavy snow brought fresh chaos to parts of Europe, snarling transport networks and leaving at least 21 people dead and hundreds stranded and without power.
Fifteen people in Poland have died this week as a result of the unrelenting cold, a spokesperson for the country's Government Center for Security told CNN Friday.
Six people have also died in Spain, according to the Spanish interior ministry.
Snow and ice continues to cause problems with air passengers facing cancellations and delays.
Geneva Airport suspended all flights for a second consecutive day as snowstorms continued to rage in Switzerland.
Flights from Amsterdam's Schiphol Airport are being delayed and canceled. In Ireland, airlines have suspended all flights to and from Dublin Airport until Saturday, and the Shannon, Cork and Kerry airports are closed until then.
15 people have died in Poland as a result of the freezing temperatures, according to authorities 6 people have died in Spain, according to the interior ministry Airports closed and flights canceled across Europe British army drafted in to help stranded motorists and National Health Service.
British army deployed
In Britain, the army was deployed late Thursday to help hundreds of motorists stranded on the country's motorways, while some rail travelers were trapped overnight as temperatures plummeted.
Parts of the UK struggled once more Friday as freezing winds from Siberia -- dubbed the "Beast from the East" -- combined with Storm Emma to bring additional snow and ice.
There are also flood warnings in place in the southwest of the country.
Roads are particularly treacherous. Chelsea Seeds and Francesca Goodall told CNN that they were trapped on the M27 and A31 near Cadnam in the southern English county of Hampshire for eight hours overnight.
Their journey from south London to Bournemouth, which would normally take around two hours, lasted 12 instead.
But even in freezing conditions, people in the area rallied to help those stuck in their cars.
"The locals at Cadnam were amazing," Goodall said.
"They had a Scout hut set up as a drinks station. They also had baby formula and nappies. Another guy was handing out bananas and another offering blankets and his own home for a a place to stay overnight. The kindness was unreal."
In northern England, police said at one point 3,500 vehicles were stuck on the M62 freeway with 200 remaining there overnight.
Rail passengers also suffered, with some trains left stranded for hours.
The army is helping transport medical staff across the country in an effort to reach the most vulnerable.
"The armed forces are assisting emergency services in ensuring essential (National Health Service) staff are able to get to work and carry out their work in local communities and are standing by to help the police and civil authorities across the UK following heavy snowfall," a spokesperson for the Ministry of Defence said.
"We are also aware of armed forces personnel volunteering in their own time with their own vehicles to help those in need."
Hundreds of schools remain closed across the country, while Britain's National Health Service remained hugely busy.
'Risk to life'
After issuing a rare red weather warning Thursday, the UK Met Office has downgraded its alert to amber and yellow across most of the UK.
Frequent and heavy snow showers could block roads and cause transport delays. Some rural communities could be cut off for days, the Met Office warned.
Up to 50 centimeters (19½ inches) of snow are expected in Dartmoor and Exmoor in southwest England and in upland parts of southeast Wales on Friday morning.
Storm Emma has battered Ireland, where a red weather warning has been in place since Wednesday night. Train and bus services have been canceled.
Weather warnings are also still in place across much of central and southern Europe, with red warnings for extreme low temperatures or snow and ice issued in Hungary and Serbia, according to Meteoalarm.
Both British Airways and Ryanair, which have canceled multiple flights to and from British airports, said they are working to rebook customers on future flights.
Rail travelers in the UK are also facing significant disruption. London's Paddington Station was closed temporarily Thursday morning because of a build-up of ice and snow on the platforms and multiple routes across the country are affected.
Drivers were urged not to venture out in areas hit by deep snow.
National Grid UK, which manages the distribution of electricity and gas across England and Wales, said Thursday there were gas supply losses overnight "due to the extreme weather conditions" and issued a gas deficit warning.
Why is this extreme weather happening?
Much of Europe has been blanketed in snow this week, with rare falls of the icy stuff in the south of France, Spain and Italy.
According to Simon Clark, researcher of stratosphere-troposphere interactions in Bristol, England, the current cold snap was triggered by a disruption to the stratospheric polar vortex -- a doughnut of air 6,000km (3,800 miles) across that forms high up in the atmosphere above the Arctic Circle every winter.
Now and again -- perhaps six times every decade -- the vortex gets split in two, a phenomenon known as sudden stratospheric warming.
The disruption allows icy Arctic air to spread further south, often lowering temperatures across much of the northern hemisphere.
"That big mass of Arctic air -- which is normally trapped over the poles, so it's really freezing cold -- is then able to spill further south," Clark told CNN.
Storm Emma, currently making its way across the UK from the southwest, is a normal phenomenon for this time of year, and would usually result in heavy rainfall.
But as it meets the freezing polar air swirling around much of Britain, the storm is much more likely to dump its moisture as snow, Clark explained.
Conditions are expected to improve by the end of the weekend, but average temperatures across the UK could remain lower than normal over the next month as the polar air gradually returns to the Arctic.
Clark expects Europe to feel the effects of disruptions to the vortex more often as the global climate continues to warm.
"It's very difficult to say for sure whether this one event was caused by climate change," he said, "but as the climate warms, we expect the polar vortex to get weaker.... We will then see more of these sudden warmings."
Precise predictions are difficult, however, due to the rate at which the climate is changing. "It's changing faster than we can collect data on it," Clark said.
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