Tourists take pictures as they walk on a snow-covered path near the Eiffel Tower in Paris, as winter weather with snow and freezing temperatures arrive in France, February 6, 2018. (Photo by Gonzalo Fuentes/Reuters)





A man walks with his dog through a forest during a foggy morning in Bern, Switzerland March 4, 2018. (Photo by Stefan Wermuth/Reuters)





The rising sun illuminates trees near the Bavarian village Eisenberg, Germany, Friday, June 15, 2016. (Photo by Karl-Josef Hildenbrand/DPA via AP Photo)





People jog along the banks of the Sevre nantaise river in Vertou, outside Nantes on January 26, 2018. (Photo by Loic Venance/AFP Photo)





Mist hangs in the Valley near Amberley in the South Downs National Park on October 3, 2018 in Amberly, United Kingdom. (Photo by Dan Kitwood/Getty Images)





Buildings are seen as fog blankets the city of Skopje, Macedonia December 15, 2017. (Photo by Ognen Teofilovski/Reuters)





Salisbury Cathedral, in the centre of the city in which former Russian intelligence officer Sergei Skripal and a woman were found unconscious after they had been exposed to an unknown substance is seen at dawn in Salisbury, March 7, 2018. (Photo by Toby Melville/Reuters)





A competitor runs during the Bolivia Sky Race on the “Death Road” from Yolosa to Chuspipata, near La Paz, Bolivia, July 29, 2018. (Photo by David Mercado/Reuters)





A cyclist rides before dawn with the moon behind in Richmond Park in west London, Britain, September 26, 2018. (Photo by Toby Melville/Reuters)





A red deer stands in the early morning mist in Bushy Park in London, Britain, October 10, 2018. (Photo by Henry Nicholls/Reuters)





The dome of Saint Peter's Basilica is seen covered in fog, before Pope Francis' weekly general audience in Saint Peter's Square at the Vatican on November 14, 2018. (Photo by Max Rossi/Reuters)





The TV Tower of Ujudvar is seen in the dense fog in Ujudvar, Hungary, 05 November 2018. (Photo by György Varga/EPA/EFE)





Aerial view of advection fog surrounding buildings on November 8, 2018 in Yuncheng, Shanxi Province of China. (Photo by Shang Jianzhou/VCG via Getty Images)





A view of the European side of Istanbul's skyline, at sunset Saturday, March 10, 2018. The Bosphorus Strait divides the Turkish historic metropolis into the European and Asian sides. (Photo by Emrah Gurel/AP Photo)





A commuter ferry crosses the Hudson River to New York City, Wednesday, April 5, 2017, in this photo from Hoboken, N.J. Many commuters are shifting to the ferry service following Monday's derailment of a NJ Transit train which has lead to reduced train service into New York. (Photo by Mark Lennihan/AP Photo)





The aerial photo of the WWII memorial taken through morning fog during sunrise in Ukraine's capital Kiev, Ukraine, Saturday, November 10, 2018. (Photo by Evgeniy Maloletka/AP Photo)





Vehicles pass through the heavy fog and air pollution that cover Skopje valley in the early morning, in Skopje, The Former Yugoslav Republic of Macedonia, 14 December 2017. According to media reports, Skopje is considered one of the most polluted cities in the world. (Photo by Georgi Licovski/EPA/EFE)





Mist flowing over the Basilica of St. Peter and St. Paul in Vysehrad, Prague on November 15, 2018. (Amos Chapple/Courtesy Images)





People walk on trocadero plaza in front of the Eiffel tower in the fog on december 19, 2017, in Paris. (Photo by Ludovic Marin/AFP Photo)





A woman stands next to a Victoria Harbour shrouded in fog in Lei Yu Mun in Hong Kong, China, 04 March 2018. In March the weather in Hong Kong is usually foggy as the humidity as the temperature go up. (Photo by Jerome Favre/EPA/EFE)