Israeli soldiers cry during a state memorial ceremony marking two years since the 2014 Gaza war “Operation Protective Edge” at Mount Herzl military cemetery in in Jerusalem, Israel, 26 July 2016. More than 2.000 people were killed in the conflicts between Israel and Palestine. (Photo by Abir Sultan/EPA)

Party-goers partake in a festival better known as Holi One, during International Workers Day in Johannesburg, South Africa, 01 May 2015. The colour festival promotes togetherness as well as colourness in everday life. May Day is observed worldwide every year on 01 May. (Photo by Kevin Sutherland/EPA)

“Contrails (short for “condensation trails”) or vapour trails are artificial clouds that are the visible trails of condensed water vapour made by the exhaust of aircraft engines. As the hot exhaust gases cool in the surrounding air they may precipitate a cloud of microscopic water droplets or, if the air is cold enough, tiny ice crystals”. – Wikipedia

Photo: An airplane leaves a vapor trail as it flies in front of he moon on January 17, 2007 above Hanover, Germany. (Photo by Alexander Hassenstein/Getty Images)

Revellers attend the Victorian Picnic during the Wave and Goth festival in Leipzig, Germany, May 22, 2015. The annual festival, known in Germany as Wave-Gotik Treffen (WGT), features over 100 bands and artists in venues all over the city playing Gothic rock and other styles of the dark wave music subculture. One of the biggest of its kind, the event attracts a regular audience of up to 20,000, the organisers said. (Photo by Hannibal Hanschke/Reuters)

Girls play in the makeshift refugee camp at the northern Greek border point of Idomeni, Greece, Thursday, March 17, 2016. Leaders of the EU's 28 divided nations reconvene in Brussels in hopes of ironing out disagreements on a proposed agreement with Turkey in the migrants crisis. (Photo by Vadim Ghirda/AP Photo)

A woman leaves sauna during the sauna marathon in Otepaa, Estonia on February 2, 2019. Participants have to track down, locate and visit designated saunas in the Otepaa area as fast as possible during the event. The team that completed all of the saunas in the shortest time wins. (Photo by Ints Kalnins/Reuters)

A Pakistani child, whose family was displaced by 2010 floods from a village in Pakistan's Sindh province, sits on a wooden cart outside her family's makeshift home, in a slum on the outskirts of Islamabad, on February 8, 2013. (Photo by Muhammed Muheisen/AP Photo)

A boat commutes across the Mekong river in Phnom Penh on August 8, 2014. The Mekong is the world's twelth longest river running from the Tibetan Plateau through China's Yunnan province, Myanmar, Laos, Thailand, Cambodia and Vietnam. (Photo by Tang Chhin Sothy/AFP Photo)