“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)

Mary McHugh mourns her slain fiance Sgt. James Regan at “Section 60” of the Arlington National Cemetery May 27, 2007. Regan, a US Army Ranger, was killed by an IED explosion in Iraq. (Photo by John Moore/Getty Images)

A steam traction engine with a broken rear axle in Pall Mall, London. (Photo by Topical Press Agency/Getty Images). November 1923

An innovative photographer attached a camera to a remote-controlled car, allowing him to capture angles of wild lions, rhinos and other animals. Over the last 11 years, Chris Bray has been taking pictures of animals using his toy car contraption while he takes guests on photography tours in Kenya. (Photo by Chris Bray/Caters News Agency)

Local residents take part in the celebrations of Kolyada pagan holiday, which over the centuries has merged with Orthodox Christmas festivities and marks the upcoming end of winter, in the village of Noviny, Belarus, January 21, 2017. (Photo by Vasily Fedosenko/Reuters)

A woman dressed as a zombie participates in an event to promote the Spanish release of the movie “Resident Evil: The Final Chapter” in Madrid, Spain, January 28, 2017. (Photo by Susana Vera/Reuters)

A couple participates in the “Running of the Brides” race in a park in Bangkok, Thailand on March 25, 2017. (Photo by Athit Perawongmetha/Reuters)

Scared of Heights. “Taken from the highest residential building in Asia: the Zenith in Busan. This was taken with official permission (which took me months to get) and safety measures were taken. I had to hang myself over the edge to get this shot. Not for the faint of heart! But when you’re at a height like this, the world below you just seems different. It takes away the fear one would normally have, and gives a sense of peace instead”. (Photo by Albert Dros/NatGeo Cities Travel Photographer of the Year 2017)