Indonesian soldiers take part in a handling riots practice ahead of the elections at their military home base in Banda Aceh, Aceh province on April 9, 2019. (Photo by Chaideer Mahyuddin/AFP Photo)

American model Bella Hadid celebrating her 23rd birthday at L’Avenue at Saks Fifth Avenue New York, NY on October 10, 2019. (Photo by David Warren/Sipa USA)

A swan sits on her eggs on nest made of rubbish found in the Danube river in Belgrade, Serbia on Monday, May 10, 2022. (Photo by Darko Vojinovic/AP Photo)

Canadian actress and model Shay Mitchell enjoys time to herself after giving birth in the last decade of August 2022. (Photo by shaymitchell/Instagram)

Germany's Darja Varfolomeev competes with a ribbon during the individual apparatus final at the 41st FIG Rhythmic Gymnastics World Championships at Carioca Arena, in Rio de Janeiro, Sunday, August 24, 2025. (Photo by Bruna Prado/AP Photo)

Kids in fancy dress eat for free at Asda Cafés in Leeds, UK on Halloween on 31st October, 2025 – a real treat for families this spooky season. (Photo by Doug Jackson/PinPep)

“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)

A child walks to an installation made from fallen leaves by college students, in shape of a sofa, to call for people's attention to environment protection, in Hangzhou, Zhejiang province, China, December 6, 2016. (Photo by Reuters/China Daily)