Apple CEO Steve Jobs delivers the keynote address at the 2011 Apple World Wide Developers Conference at the Moscone Center on June 6, 2011 in San Francisco, California. Apple CEO Steve Jobs returned from sick leave to introduce Apple's new iCloud storage system and the next versions of Apple's iOS and Mac OSX. (Photo by Justin Sullivan/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)

Space Shuttle Discovery leaves the Vehicle Assembly Building (VAB) on its way to the Orbiter Processing Facility at Kennedy Space Center August 11, 2011 in Cape Canaveral, Florida. Space Shuttles Endeavour and Discovery switched buildings as they are being decommissioned with the end of the Shuttle program. (Photo by Roberto Gonzalez/Getty Images)

Arsenal football supporters cheering from the train carriage window as they leave Euston Station, London, on their way to Birmingham for their team's match against Aston Villa which they lost 3-5. (Photo by Douglas Miller/Topical Press Agency/Getty Images). 19th November 1932

Aymara witchdoctor Ricardo Quispe, also called “Lord of the Lake”, throws coca leaves during a ritual to predict the future, at the witches market of El Alto, on the outskirts of La Paz, December 31, 2014. Dozens of witch doctors tend to a warren of stalls in El Alto, making offerings to give thanks, to promise luck at work or in love, or to call up spirits and banish curses at the end of the year. (Photo by David Mercado/Reuters)

Anand Varma, a U.S. photographer working for the National Geographic, won the First Prize in the Nature Category, Stories, of the 2015 World Press Photo contest with his series of pictures, which includes this one of spores of a fungus landing on an ant, penetrating its exoskeleton and entering its brain, compelling the host to leave its normal habitat on the forest floor and scale a nearby tree, in this picture taken January 22, 2014 and released by the World Press Photo on February 12, 2015. (Photo by Anand Varma/Reuters/National Geographic/World Press Photo)

Cars pass a tank position close to the Russian border near the Ukrainian city of Kharkiv March 24, 2014. U.S. President Barack Obama sought support from European allies and China on Monday to isolate Russia over its seizure of Crimea, and Ukraine told its remaining troops to leave the region after Russian forces overran one of Kiev's last bases there. (Photo by Dmitry Neymyrok/Reuters)

People look at the Harmony of the Seas cruise ship leaving the STX shipyard of Saint-Nazaire, western France, for a three-day test offshore, on March 10, 2016. With a capacity of 6.296 passengers and 2.384 crew members, the Harmony of the Seas, built by STX France for the Royal Caribbean International, is the world's largest ship cruise. (Photo by Loic Venance/AFP Photo)