A fado singer smokes a cigarrette outside a fado house at the Alfama neighborhood in Lisbon on May 8, 2019. From fado sounds to Cape Verde mornas or bossa nova: the Lisbon nights, where musicians from all over the world meet, have largely inspired Madonna's new album, who has been in the Portuguese capital since 2017. (Photo by Patrícia de Melo Moreira/AFP Photo)

The buildings of the banking district are seen through thousands of rain drops on a glass railing in central Frankfurt, Germany, Wednesday, January 11, 2017. (Photo by Michael Probst/AP Photo)

Keith Richards, Mick Jagger, Ron Wood of the Rolling Stones perform during their "14 on Fire" show at Waldbuehne in Berlin, June 10, 2014. REUTERS/Thomas Peter

A couple wears face masks as they share a moment during sunset on January 31, 2020 in Hong Kong, China. With over 9800 confirmed cases of Novel coronavirus (2019-nCoV) around the world, the virus has so far claimed over 200 lives. (Photo by Anthony Kwan/Getty Images)

The Royal Castle is seen a veil of heavy winter smog in Budapest, Hungary on January 30, 2017. (Photo by Laszlo Balogh/Reuters)

Chinese artist Kong Ning walks in her costume made of hundreds of orange plastic blowing horns during her art performance raising awareness of the hazardous smog in front of the Drum tower in a historical part of Beijing on a very polluted day December 7, 2015. Kong, whose works include themes related to China's air pollution problem, named her new performance “The Orange Horns Bride Marries the Blue Sky” and presented it dressed in orange, the colour of the second highest pollution alert level issued again in Beijing as hazardous smog blankets the capital. (Photo by Damir Sagolj/Reuters)

Located in East Java, Indonesia, Kawah Ijen is a volcano is home to the largest acidic crater lake in the world. What turns the waters of the lake in the 1 km caldera its beautiful turquoise color are the highly sulfuric gases emitted from the volcano underneath.

People take photos with the skyline of the central business district in Singapore on September 10, 2015. (Photo by Edgar Su/Reuters)