Arctic temperatures grip US Midwest

Freezing temperatures have gripped the northern United States due to a split in the polar vortex, a mass of cold air that normally stays bottled up in the Arctic. The Wednesday morning temperature in Chicago was -30 degrees Celsius (-22 Fahrenheit) which felt like -46 degrees with the wind chill. It was expected to get down to -33 degrees on Thursday.

The weather wreaked havoc on airports and train services. More than 1,800 flights were cancelled at Chicago's two major airports, while rail operator Amtrak cancelled train services from its hub in the city. At Chicago's O'Hare airport, ground crews were told to avoid spending more than 15 minutes at a time exposed to the freezing air, which delayed the lucky flights that managed to take off.

Commuters heading to work in Chicago had to layer up to fend off the cold. "I have two shirts on... I have a hoodie, I have my big winter coat, I have a face mask and a skullcap and I am still cold," sandwich shop manager Daniel Gonzalez said.

The dangerously low temperatures killed several people, including a University of Ohio student, and an 82-year-old man who fell as he approached his front door. "This is a historic cold, obviously," Chicago Mayor Rahm Emanuel said. "They are life-threatening temperatures, and they should be treated accordingly," he cautioned

Despite the bitter cold, daily activities have to continue. The outside temperature was -28 degrees at Metogga Lake Dairy on Wednesday and staff started milking 412 cows at 4 o'clock in the morning.

Hundreds of warming centers were opened for vulnerable residents such as seniors. Buses were used as mobile warming spaces, and shelter capacities were increased for the homeless, including the approximately 16,000 living on the streets of Chicago. The dangerously cold wind chills could cause frostbite on exposed skin in as little as five minutes," the National Weather Service said.

The weather affected other essential services, including the postal system and blood donations. The US Postal Service suspended deliveries in parts of Indiana, Michigan, Illinois, Ohio, Iowa, the Dakotas and Nebraska. The American Red Cross had to cancel 370 blood drives, which was expected to lead to an estimated 11,600 in uncollected blood donations for the month of January.

When temperatures get below around -35 degrees Celsius, water can freeze instantly. Here someone has tried to blow a bubble, but it has swiftly transformed into ice as it met the cold air.

As temperatures dipped, Glenn and Julia Auerbach invited their friends Dan Wilson and Omina Shibahara over to their Minneapolis home for a backyard sauna. The hot room was over 100 degrees warmer than outside.