Long-tailed mayflies (Palingenia longicauda) mate on the surface of the Tisza river near Tiszakurt, Hungary, June 14, 2016. Millions of these short-lived mayflies engage in a frantic rush to mate and reproduce before they perish in just a few hours during “Tiszaviragzas” or Tisza blooming season from late spring to early summer every year. (Photo by Laszlo Balogh/Reuters)

A model poses backstage during the International Flamenco Fashion Show in Seville, Spain, on February 2, 2013. (Photo by Associated Press/Miguel Angel Morenatti)

Anime fans visited the Hyatt Regency Milwaukee on the weekend of February 15-17 for Anime Milwaukee 2013. (Photo by Pat A. Robinson)

A devotee participates in Holi celebrations at the Nandagram temple, on March 22, 2013. (Photo by Manish Swarup/Associated Press)

Cars at a car dealership are seen in the flooded village of Fischerdorf, near Deggendorf June 7, 2013. REUTERS/Michaela Rehle

Contestant of the Muslimah World 2013, Obabiyi Aishah Ajibola (C) of Nigeria, is reflected in a mirror checking her make-up while contestants wait for a grand final during the Muslimah World competition in Jakarta on September 18, 2013. (Photo by Adek Berry/AFP Photo)

“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)