The US Midwest is in the grip of an extremely cold spell of winter, christened the Polar Vortex. In Chicago, temperatures have touched a low of minus 30 degrees Celsius, and the surface of the Chicago River has frozen in parts. According to USA Today, eight people have died because of the extreme weather conditions. The wind chill dipped to touch minus 51 degrees.

No wonder people are having to improvise to survive and go about their daily activities.

In Michigan, a student was recorded skiing to classes in the snow a few days ago.

Like Illinois, Michigan is also reeling under freezing conditions.

Here is an explanation of what it is all about.