From a distance, its easy to see how snow brought so much of mainland life to a standstill.

The blanket of snow that cut power, closed schools and blocked roads in the South Island has been captured in a satellite image this morning.

NIWA scientist Richard Turner said the image taken at 10.48am today showed Canterbury got a "good dumping" of snow to fairly low elevations yesterday.

"You can see the elevation that the snow reached, though there would have been a wee bit of melting by then," he said.

"There is a bit of snow even on the ranges around Nelson, up to the back of Takaka. It just shows the scale of the weather system.

"In the Tasman, there is a lot of clumpy clouds that shows very cold air over a relative warm ocean."

Turner said it was clear on both the east and west of the South Island, suggesting there was southwesterly flow following the storm.

He said geographical features stood out after a snow fall, with rivers and ranges easy to spot in the image.

"It's a nice image, it would have been quite frosty last night, quite cold this morning. There are a lot of things you can see."

The image was captured using data from a sensor flying aboard Nasa's Earth Observing System satellite Terra, and was then received by Niwa's station in Central Otago.

Aquat and Terra passes over New Zealand twice a day - once during the daytime and again at night - at an altitude of 705km.

Power was restored to most households today and flights resumed at Christchurch Airport, although some disruption continues.

Cantabrians were today urged to take extreme caution as ice and frost added to the difficulties caused by up to a metre of snow.

Buses were running again in Christchurch today, but some routes had changed.

People were advised that if they did not need to drive, they should stay home.

Some schools remained shut  and Lincoln University cancelled today's exams, saying students who were meant to sit exams will receive an aegrotat consideration.

- © Fairfax NZ News