Morning fog embraces the trees of the City Park of Budapest, Hungary, Feb. 3, 2017. Zoltan Balogh/EPA

Fog is seen over over the Jested mountains, Czech, Republic in January 2017. Martin Rak/Solent News/REX/Shutterstock

The sun rises as blanket of fog covers the Aleppo citadel and the city of Aleppo, Syria, Jan. 20, 2017. Hassan Ammar/AP Photo

City of Edinburgh shrouded in frozen fog in Edinburgh, Scotland, Jan. 21, 2017. Geoff Robinson Photography/REX/Shutterstock

The Eiffel Tower in Paris, France, in a heavy fog, Jan. 31, 2017. Ludovic Marin/AFP/Getty Images

A deer jumps through a field at sunrise in Popielarze village near Warsaw, Poland, Jan. 27, 2017. Janek Skarzynski/AFP/Getty Images

Fog is seen over the Bavarian city of Garmisch-Partenkirchen, Germany, Jan. 20, 2017. Christof Stache/AFP/Getty Images

The Ayrton Light is seen lit above the belfry in Elizabeth Tower, commonly known as Big Ben, on Feb. 1, 2017 in London, England. Chris J Ratcliffe/Getty Images

Lake Constance covered in dense fog, Feb. 2, 2017. Felix Kastle/AFP/Getty Images

A pedestrian walks through the winter fog in temperatures in Berlin, Germany, Feb. 1, 2017. Maurizio Gambarini/dpa Photo via Newscom

A man walks in fog in Dunham Park near Altrincham in Britain, Jan. 23, 2017. Phil Noble/Reuters

A blanket of fog covers the city of Sofia, Bulgaria, Jan. 21, 2017. Blagoy Kirilov/Reuters