Mr. Grindell Matthews with his latest invention, the new photographic gun which is the latest development in sky signs. 1933. It can throw a beam of light 15 miles into the sky. (Photo by Fox Photos)

Dark clouds bearing down on the city on April 17, 2011 in Foshan, Guangdong Province of China. According to flood control authorities on Monday, gales as strong as 45.5 meters per second, accompanied by hailstorm, cloudburst and strong wind battered cities including Guangzhou, Foshan, Zhaoqing and Dongguan of south China's Guangdong Province on Sunday, has killed at least 17 people and injured 118. (Photo by ChinaFotoPress/Getty Images)

West German police arrest a young man, one of the angry crowd throwing stones at a bus full of Soviet guards making their way to the Soviet War Memorial, 20th August 1962. The crowd were incensed by the death of 18-year-old Peter Fechter, who was shot while trying to cross the Berlin Wall a few days earlier. (Photo by Central Press/Hulton Archive/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)

Australian actress Joy Smithers poses beside a poster featuring Australian cricketer Brett Lee during the official launch of the AceStar underwear range at Pink Salt on August 19, 2008 in Sydney, Australia. (Photo by Mike Flokis/Getty Images)

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

Young Palestinians form an obstacle to be jumped over during a military-style exercise graduation ceremony organised by the Hamas movement, in Gaza City August 5, 2015. Thousands of young Palestinians joined Hamas military-style summer camps during school vacation in the Gaza Strip to prepare them to “confront any possible Israeli attack”, organisers said. (Photo by Suhaib Salem/Reuters)

Tippi aged 6 sitting on the back of Linda, a tamed ostrich in South Africa, 1996. Incredible pictures of the real life Mowgli, a girl who spent the first ten years of her life growing up in the African bush, have been released for the first time. The magical images chronicle the life of Tippi Benjamine Okanti Degré, who was brought up with wild animals, just like Rudyard Kipling's hero did in The Jungle Book. (Photo by Sylvie Robert/Barcroft Media)