20140109 BBC_North America's big freeze seen from space

Satellite images have captured the progress of the big freeze that has gripped the United States and Canada, plunging many states into unfamiliar freezing temperatures.

4 January

The most extreme arctic blasts, blamed on a shift in the weather pattern known as the "polar vortex", sent colder air further south than usual.

7 January

Satellite images from 7 January show cloud off the east coast - more than 191 million are believed to have been affected by the cold weather, at least 21 have died as a result. Forecasters are now expecting the eastern US to warm a little - although some still face temperatures 15-25 degrees below average.

North America's big freeze seen from space