“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 Royal Air Force search and rescue helicopter prepares to leaves RAF Valley as the search continues for the crew of cargo vessel The Swanland which sank off north Wales on November 27, 2011 in Anglesey, Wales. (Photo by Christopher Furlong/Getty Images)

Participants take part in the annual Great Spitalfields Pancake Race in aid of London's Air Ambulance in London, Britain February 9, 2016. (Photo by Stefan Wermuth/Reuters)

A rescue worker holds an injured boy after what activists said were airstrikes carried out by the Russian air force in Idlib city, Syria December 20, 2015. (Photo by Ammar Abdullah/Reuters)

A woman jumps in the air as she poses for a photo during New Year celebrations in the Manhattan borough of New York, January 1, 2016. (Photo by Carlo Allegri/Reuters)

Haitian soldiers shoot in the air to try to control the crowd as they wait for food to be handed out after Hurricane Matthew hit Jeremie, Haiti, October 18, 2016. (Photo by Carlos Garcia Rawlins/Reuters)

A riot policeman fires into the air during clashes with opposition supporters at a rally demanding a referendum to remove President Nicolas Maduro in Caracas, Venezuela, May 11, 2016. (Photo by Carlos Garcia Rawlins/Reuters)

President Barack Obama with does the tango with a dancer during the State Dinner at the Centro Cultural Kirchner, Wednesday, March 23, 2016, in Buenos Aires, Argentina. (Photo by Pablo Martinez Monsivais/AP Photo)