“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)

Emma Watson poses at the winners boards at the Sony Ericsson Empire Film Awards at the Grosvenor House Hotel on March 9, 2008 in London England. (Photo by Dan Kitwood/Getty Images)

Impala pictured in the Kruger National Park on December 7, 2007 in Mpumalanga, South Africa. (Photo by Warren Little/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)

7 year old Soni has a basket of coal lifted onto her head by her mother, 28 year old Savita, after having scavenged coal illegally from an open-cast coal mine in the village of Bokapahari on February 08, 2012 near to Jharia, India. (Photo by Daniel Berehulak /Getty Images)

A firefighter holds a red panda (Ailurus fulgens) from its tail while removing it from a tree at a residential area in Kunming, Yunnan province, July 3, 2014. The animal was spotted in the residential area and was brought down from the tree after residents reported its sighting to the police, local media reported. (Photo by Reuters/Stringer)

Medieval jousters Luke Binks (L) and Andrew McKinnon pose for a photograph in Sydney, Australia, August 16, 2017 during a photo call for the World Jousting Championships to take place in Sydney on September 23 and 24. (Photo by Dan Himbrechts/Reuters/AAP)

A woman poses with her tattoo during the Shanghai Tattoo Extreme & Body Art Expo 2017 in Shanghai, China September 2, 2017. (Photo by Aly Song/Reuters)