It might have been foggy in the Willamette Valley, but Cerridwen Martin was able to revel in a view of the top of the clouds from the summit of Spencer Butte in Eugene, Ore., on Tuesday, December 16, 2014. Martin was joined by Joe Martinson, right, for the 1.1 mile trek. Fog shrouded much of the city for most of the day. (Photo by Andy Nelson/AP Photo/The Register-Guard)

A view of the fireworks during the Edge at Hudson Yard's 4th of July Celebration at Edge at Hudson Yards on July 04, 2021 in New York City. (Photo by Roy Rochlin/Getty Images for Edge at Hudson Yards)

in Qayyarah, about 31 miles (50 km) south of Mosul, Iraq, Sunday, October 23, 2016.in Qayyarah, some 50 kilometers south of Mosul, Iraq, Sunday, Oct. 23, 2016. Islamic State fighters torched a sulfur plant south of Mosul, sending a cloud of toxic fumes into the air that mingled with oil wells the militants had lit on fire to create a smoke screen. (Photo by Marko Drobnjakovic/AP Photo)

A police officer wearing a protective mask walks past the portrait of late communist leader Mao Zedong (not pictured) at Tiananmen Gate in Beijing on January 23, 2020. Large-scale Lunar New Year events in Beijing have been cancelled as part of national efforts to control the spread of a new SARS-like virus, city authorities announced on January 23. (Photo by Nicolas Asfouri/AFP Photo)

A large teddy bear, used to enforce social distancing, is pictured sitting at a cafe in Pristina on July 23, 2020, as Kosovo authorities announce new measures to fight against the resurgence of the COVID-19, the novel coronavirus. (Photo by Armend Nimani/AFP Photo)

Actors dressed up as zombies walk around while posing for photos with passers-by in New York's Times Square on Friday, October 10, 2014 as a promotion for the season premiere of AMC's “The Walking Dead” this Sunday, October 12, 2014. (Photo by Gordon Donovan)

Revellers take part in the the 70th Annual Columbus Day Parade in New York, October 13, 2014. (Photo by Eduardo Munoz/Reuters)

Growing cities, overuse of fertilizers and factory wastewater have degraded China's water supplies to the extent that half the nation's rivers and lakes are severely polluted. China aims to spend $850 billion to improve filthy water supplies over the next decade, but even such huge outlays may do little to reverse damage caused by decades of pollution and overuse in Beijing's push for rapid economic growth. Photo: Fishermen row a boat in the algae-filled Chaohu Lake in Hefei, Anhui province, June 19, 2009. (Photo by Jianan Yu/Reuters)