A wounded member of the Afghan police reaction force waits for treatment in Alingar, Laghman province, on April 30, 2012. A bomb exploded next to opium poppy fields during a poppy eradication campaign in, wounding two Afghan policemen, police officials said. (AP Photo/Rahmat Gul)

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

Protesters wearing masks perform during anti-austerity and anti-graft protests in Ljubljana, Slovenia, on January 11, 2013. More than 5,000 Slovenians gathered in the center of Ljubljana on Friday to protest against a corruption scandal that threatens to bring down the government. Slovenia's anti-corruption commission said earlier this week that Prime Minister Janez Jansa had been unable to explain the source of some of his income in recent years. (Photo by Srdjan Zivulovic/Reuters via The Atlantic)

A young oriental small-clawed otter at the zoo in Neumuenster, Germany, March 5, 2014. The six young otters (one male, five female) were born on December 7, 2013. (Photo by Maja Hitij/EPA)

Robert Price of TREWGrip LLC demonstrates a TREWGrip handheld rear-type keyboard and air mouse for Apple and Android tablets at the “CES: Unveiled”, media preview for International CES, at the Mandalay Bay Convention Center in Las Vegas on January 5, 2014. (Photo by Robyn Beck/AFP Photo)

Mazda Motor introduces the company's concept vehicle, Taiki during the press day of the 40th Tokyo Motor Show at Makuhari Messe, on October 24, 2007 in Chiba Prefecture, Japan. (Photo by Koichi Kamoshida/Getty Images)

“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)