Performers line up during the closing ceremony of the 2014 Winter Olympics, Sunday, February 23, 2014, in Sochi, Russia. (Photo by Darron Cummings/AP Photo)

The rising sun penetrates early morning mist and begins to burn off the first frost of winter in the Cheshire countryside at dawn on 24 October, 2007, Knutsford, England. (Photo by Christopher Furlong/Getty Images)

An Zi, is squashed amongst other commuters in a subway train on his way to work in Beijing, China, November 12, 2015. An, a movie producer, moved to Dongsanqi village in Changping this year. His commute to work can take about 2 hours, with transportation costs topping 200 yuan a month, or about a fifth of his monthly rent. (Photo by Jason Lee/Reuters)

A woman from the Tarahumara ethnic group cuts firewood with an ax while preparing for winter in Caborachi village, in Guachochi, Mexico, December 17, 2016. (Photo by Jose Luis Gonzalez/Reuters)

A member of security personnel stands on duty on an empty train platform inside a station on the Subway Line Number 1 on the eve of the Chinese Lunar New Year, in Beijing, China, February 7, 2016. According to local media, traffic in Beijing has seen a rare relief from its usual heavy pressure after 15 million people have left the city, heading for family reunions in their hometowns on the eve of the Chinese Lunar New Year of Monkey. (Photo by Jason Lee/Reuters)

A sledding dog is covered in ice after spending the night in the open air with his musher at the polar base of Val-Cenis, as they ready for the next stage of the 12th edition of “La Grande Odyssee” sledding race across the Alps on January 17, 2016 in Val Cenis Lanslevillard. (Photo by Jean-Philippe Ksiazek/AFP Photo)

A reveller wearing a golden cape celebrates as the sun rises during the winter solstice at Stonehenge on Salisbury plain in southern England December 22, 2014. The winter solstice is the shortest day of the year, and the longest night of the year. (Photo by Dylan Martinez/Reuters)

Homeless people queue to get free hot food organized by social services during frost winter day in-Kiev on December 18, 2012. Nineteen people died of exposure in Ukraine in the last 24 hours amid temperatures of minus 20 degrees Celsius (minus 4 degrees Fahrenheit), bringing the toll this month to 37, the health ministry said Tuesday. (Photo by Sergei Supinsky/AFP Photo)