Runners rest inside Kim Il Sung Stadium in Pyongyang, North Korea on Sunday, April 14, 2013. North Korea hosted the 26th Mangyongdae Prize Marathon to mark the upcoming April 15, 2013 birthday of the late leader Kim Il Sung. (Photo by Alexander F. Yuan/AP Photo)

In this photo provided by The Daily Free Press and Kenshin Okubo, people react to an explosion at the 2013 Boston Marathon in Boston, Monday, April 15, 2013. (Photo by Kenshin Okubo/AP Photo/The Daily Free Press)

P.S. All pictures are presented in high resolution.

“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)

Models showcase Valentine's Day underwear celebrating the results of a recent survey revealing that men find the lingerie, boxer shorts and vests, the biggest turn on ahead of February 14 Valentine celebrations, at Waterloo on February 2, 2006 in London, England. (Photo by Gareth Cattermole/Getty Images)

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

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)