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)

Two chimpanzees share a piece of watermelon at Taronga Zoo on December 23, 2010 in Sydney, Australia. (Photo by Rick Stevens/Taronga Zoo via 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)

A polar bear fast asleep at London Zoo. (Photo by Fox Photos/Getty Images). 1961

A man pours mud water on the head of his girl friend during the Boryeong Mud Festival at Daecheon Beach in Boryeong, South Korea, Friday, July 18, 2014. The annual mud festival features mud wrestling and mud sliding. (Photo by Ahn Young-joon/AP Photo)

People celebrate France' s victory in the Russia 2018 World Cup final football match between France and Croatia, on July 15, 2018 in Toulouse' s city centre. (Photo by Eric Cabanis/AFP Photo)

A hot air balloon in the shape of children's comic Rupert Bear is seen tethered before a tethered flight at the Bristol International Balloon fiesta in south west England, Britain, August 10, 2018. (Photo by Adrian Sherratt/The Guardian)