People walk under Australia's iconic landmark Harbour Bridge in Sydney on April 3, 2019, as heavy fog blankets the city. Low visibility due to heavy fog affected traffic in the city and caused flight delays at the Sydney airport. (Photo by Saeed Khan/AFP Photo)

A relative of murdered prisoner, lies on a chair next to his coffin during a wake after a prison riot in the city of Altamira, Para state, Brazil on July 30, 2019. At least 57 prisoners were killed by other inmates during clashes between organized crime groups in the Altamira prison in northern Brazil Monday with 16 of the victims being decapitated, according to prison officials. (Photo by Bruno Kelly/Reuters)

A girl yawns as she and others wait for the start of their first day in school, an occasion known as the Day of Knowledge, in the small town Ignalina, some 110km (68 miles) north of the capital Vilnius, Lithuania, Monday, September 2, 2019. (Photo by Mindaugas Kulbis/AP Photo)

A couple sit on the terrase of a cafe in Istanbul as seagulls fly over them on September 10, 2019. (Photo by Ozan Kose/AFP Photo)

Protestors from the Extinction Rebellion march on day six of protests stopping traffic in the city district of Melbourne, Australia on October 12, 2019. (Photo by ydney Low/ZUMA Wire/Rex Features/Shutterstock)

“Winter shapes, Moscow river”. Moscow river at this part is never covered by ice. When the temperature is very low it's possible to see a strong fog. Morning light and pipes of the oli factory creates a fantastic landscape. Photo location: Moscow, Russia. (Photo and caption by Sergey Rumyantsev/National Geographic Photo Contest)

Monsoon thunderstorm in Sierra Vista, Arizona. 9 Sept, 2011. (Photo by Steven Maguire)

“Valentine Shmalentine”, 2011. (Photo by GillyFace)