An elderly man has been found dead by his partner close to a school in freezing conditions.

Robert Johnston, 79, was discovered near Panmurefield Road outside Monifieth High School in Angus on Wednesday at around 5am.

Tayside Police said the sudden death of Mr Johnston, known locally as Grahame, is not being treated as suspicious and that a report had been submitted to the procurator fiscal.

The discovery came as wintry conditions blasted Scotland with the Met Office issuing an amber alert for most of the country last night.

Four of the six regions in Scotland are under the "be prepared" snow warning while Orkney, Shetland, south-west Scotland and the Lothian and Borders area have a yellow "be aware" alert until 11am.

Transport minister Keith Brown said the multi-agency response team would monitor rush-hour travel and offer help. He said the severe weather warning suggests it could be the biggest challenge of the winter to date.

"We would remind motorists and the travelling public to be aware of the potential dangers of snow and icy conditions. An added risk is that fresh snow could fall on hard-packed ice and already-treacherous surfaces, so keep up to date with live travel information and advice for preparing for and driving in testing conditions," he said.

"The public should be prepared for the risk of significant disruption to travel, especially over the M8 corridor to the east of Glasgow, across Perthshire and over much of inland eastern Scotland."

David Simpson, route managing director of Network Rail Scotland, said: "We're monitoring the weather forecast and deploying our rapid response teams to where the weather is most likely to hit.

"In the past couple of years we've invested heavily in innovative technology such as Nasa-grade insulation to prevent points freezing and snow displacers which prevent snow building up. This will make the network as robust as possible and help us to keep Scotland moving."

Anthony Astbury, chief forecaster at the Met Office, said temperatures could drop to minus 6C widely and even lower in more rural locations.

"At lower levels, 2cm-3cm of snow is likely before turning back to rain. Despite turning to rain, the lying snow and ice will struggle to melt and this will bring some treacherous conditions," he said.

Speaking on behalf of the Association of Chief Police Officers in Scotland (Acpos), Deputy Chief Constable Tom Ewing said: "Anyone who is travelling in these areas should be prepared for possible delays and make sure their vehicle is properly prepared.

"The snow will follow a a prolonged period of low temperatures and all road users should take care and look out for ice and untreated surfaces."

More than 50 schools have been affected by snow and ice in the north east.

Two schools in Aberdeenshire have closed to all pupils and 50 have either closed to pupils having to travel or have changed the usual transport routes.

One nursery in Aberdeen city is closed to children who have to use transport because of icy roads and the threat of more snow.

Some traffic saw lengthy delays because of accidents.

Grampian Police said the A90 became "very congested" after a head-on crash in Balmedie, eight miles north of Aberdeen, in which two people were hurt.

One of the casualties managed to free himself and another man was trapped inside his vehicle with leg and pelvis injuries.

The road was closed for 20 minutes, causing lengthy tailbacks, and reopened just before 9am.

Delays were reported six miles south of Aberdeen in Portlethen where three vehicles were in an accident on the northbound slip road. One woman sustained injuries to her face.