A Boeing 777-300 from Swiss International Airlines lands on a foggy morning at Zurich Airport, on Friday, October 13, 2017, in Zurich, Switzerland. The high humidity renders the air vortex visible. (Photo by Christian Merz/Keystone via AP Photo)

In this photograph taken on April 16, 2014, a veterinary staff member of the Sumatran Orangutan Conservation Programme center conducts medical examinations on a 14-year-old male orangutan found with air gun metal pellets embedded in his body in Sibolangit district in northern Sumatra island. (Photo by Sutanta Aditya/AFP Photo)

Galagos, more commonly known as bush babies, are tiny African primates with remarkable jumping abilities. Thanks to the elastic energy stored in the tendons of their lower legs, small-eared galagos can jump 6 feet straight up in the air. (Photo by Traer Scott/Chronicle Books)

Balloons are inflated at the Bristol International balloon fiesta in south west England August 6, 2015. Now in its 37th year, the Bristol International Balloon Fiesta is Europe's largest annual hot air balloon event in the city that is seen by many balloonists as the home of modern ballooning. (Photo by Toby Melville/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)

Anti-pollution protesters wearing traditional costumes and contemporary gas masks ride bicycles in the Qingming Grand river park in Kaifeng, Henan Province, China on January 1, 2017. The Beijing Municipal Environmental Protection Bureau extended an “orange alert” for heavy air pollution for three more days. (Photo by SIPA Asia/Rex Features/Shutterstock)

People immerse themselves in an ice hole in the Chulym river, with the air temperature at about minus 12 degrees Celsius (10.4 degrees Fahrenheit), during celebrations for the Russian Orthodox Epiphany outside of the town of Nazarovo, Krasnoyarsk region January 19, 2015. (Photo by Ilya Naymushin/Reuters)

In this Wednesday, March 18, 2015 photo, limestone quarry workers walk through a cloud of dust spewed into the air by rotor blades of the stone-cutting machinery in the desert of Minya, southern Egypt. Around 45,000 people, including children, work in an estimated 1,500 quarries, digging out stones that later will be used in construction or powdered to be used by pharmaceutical and ceramic companies. (Photo by Mosa'ab Elshamy/AP Photo)