• Edinburgh is transformed into a surreal landscape by the freeze. The snow may ease in the coming days but icy conditions will stay. Picture: Neil Hanna
Much of the country's transport system was gridlocked, with the Forth Road Bridge closed by snow for the first time, key trunk roads reduced to single lanes, bus and train services cancelled and Edinburgh airport closed to arrivals all day. Dundee closed its runway for part of the day and other airports suffered heavy delays.
As frozen Scotland endured another blast of snow and ice, more than a quarter of a million children got another day off, as 11 out of 32 local authorities closed all their schools. Four councils, the Borders, plus East, West and Midlothian, said all schools would remain closed until at least Monday.
The impact of the prolonged extreme weather, which saw overnight temperatures plummet to minus 20C at the Sutherland village of Altnaharra, has begun to be felt in hospitals. Many cancelled all non-emergency operations, diverting medical staff to emergency work.
BP said the weather was affecting deliveries from the Grangemouth terminal to its petrol stations across Scotland. "Safety is BP's number one priority, so delivery vehicles are being double-manned and are only leaving the terminal when it is safe to do so," a spokesman said.
Supermarkets are struggling to maintain supplies as delivery vans battled to reach stores.
There is likely to be no let-up in the chaos as conditions are set to worsen in coming days as temperatures plummet, while snow falls will continue, especially in the North-east.
• Schools: Anger as parents get only half-hour notice of closures
• The NHS: Hundreds of hospital appointments cancelled
Click here for more coverage of the Big Freeze
The weather has forced organisers to cancel a number of events across Scotland. All Scottish Premier League games scheduled for Saturday have been cancelled, while the Glasgow Loves Christmas Choirfest in George Square was called off last night.
A concert in Aberdeen tonight featuring Aly Bain and Phil Cunningham has been axed, while the Scottish Chamber Orchestra was forced to cancel its concert in Perth last night.
Partick Retail Outdoor Market, which was to be held tomorrow, has been called off.
"Scotland is experiencing its worst snowfall at this time of year since 1965, but we are seeing the country pulling together to help overcome the extreme conditions," said justice secretary Kenny Mac-Askill.
Edinburgh council said the snowfall had been the heaviest the capital had seen since 1963, as contractors were drafted in to shift snow using diggers to clear the streets. The local authority said 2,000 tonnes of salt had been used since 25 November, and supplies stood at about 5,000 tonnes yesterday morning.
Mr MacAskill was speaking on a visit to the Stockbridge House Day Centre for the elderly in Edinburgh, where he watched offenders shovel snow. They had been switched from their usual community-service duties to help with the winter clear-up.
"I've seen offenders paying back communities they have harmed by doing some tough manual labour to help clear pavements of snow for elderly residents to allow them to get out and about safely," he said.
The Arctic weather has now spread across most of the UK. In Crawley, West Sussex, a motor-cyclist was killed in a crash involving a lorry at 5:10am yesterday, and a woman died after falling into a freezing lake at Pontefract Racecourse, Yorkshire.
Back in Scotland, the Forth Road Bridge was shut at 6:30am yesterday after a jack-knifed lorry blocked both lanes northbound, allowing heavy snow to build up. It remained closed until about 4pm.
A spokesman for the Forth Estuary Transport Authority said additional heavy snow-clearing equipment had been provided by Fife and Edinburgh councils.
"This has really been unprecedented," he said. "We are hopeful that we will be able to keep the lanes clear and that traffic travelling along the bridge during the night will keep it fairly clear, but it all depends on the weather."
Edinburgh and London Gatwick airports were both closed all day. Edinburgh, which has been criticised for failing to update travellers, said on Twitter that it had ensured its website contained the latest information "to reflect tweets".
"Edinburgh airport is still closed. We've been working around the clock to clear the runway. Thank you for your patience," airport staff tweeted.
It emerged yesterday that it had invested 1 million in new de-icing and snow-clearance equipment after last year's harsh winter left it struggling to cope.
A statement from Dundee airport said it would be closed "until further notice".
Police warned against all but "necessary" travel on Scotland's roads as stories continued to emerge of drivers getting stuck in snow drifts, while breakdown companies told of an unprecedented number of call-outs.
AA president Edmund King criticised British road and rail chiefs. "We might have more salt than last year, but we need better planning to allow gritters through heavy traffic and blocked roads," he said."Some highway authorities have invested in new gritters but again we hear that farmers offering to use tractors as snow ploughs were prevented from doing so as the insurance had not come through. This is not good enough.
"The UK has lost tens of millions of pounds over the last few days due to road stagnation and rail paralysis in some areas. We have had people trapped on motorways and on trains for hours on end and that is unacceptable."
Scotland has experienced some of its lowest temperatures in recent days.
Altnaharra was the coldest place in the UK on Wednesday, and Jean Smart, 36, manager of the Altnaharra Hotel, said the temperature had not risen above minus 6C during daylight hours yesterday. But she added: "There are clear blue skies overhead. It's a little bit of winter heaven when the freezing fog lifts. It's really beautiful just now and scenery is just fantastic."
The only problem is the hotel had no guests to share the winter wonderland. "We could do with a few customers to keep us busy and give us something to do. If people come here, they can sit by a log fire while we do all the work for them," she said.
Long time Altnaharra residents, pensioners Margaret and Frank Duffy, were also settling in to cope with the big chill. Mr Duffy said: "You've just got to live with it. I think my car is frozen up. It's just under a big ball of snow at the moment. I've not seen it for ten days."
In Angus, coastguards were drafted in to deliver meals on wheels to vulnerable residents.
Rural communities have suffered from sporadic deliveries to shops, while even major supermarkets in large cities have experienced empty shelves as people rush to stock up on essentials.
Villagers in Auchterarder, Perthshire yesterday received vital supplies of fresh meat and other produce at the local Co-op, where many of the shelves had been empty since the weekend.
The village has at times has been cut off from the outside world after experiencing some of its heaviest ever snowfalls.
Aileen Holmes, the duty manager at the Co-op said: "It was our first delivery since last Friday night. We had run out of everything. I wouldn't say there has been panic buying. But on Sunday we were trying to ration supplies - asking people if they needed all the milk they were buying for example."