“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)

David Sharp, an engineer with Lockheed Martin, displays the “Samurai Flyer”, an aviation design inspired by the maple seed, during the Association for Unmanned Vehicle Systems International Conference August 16, 2011 in Washington, DC. Lockheed Martin unveiled the new design and demonstrated vertical takeoff and landing, stable hover, and on-board video streaming of the aircraft during their demonstration. (Photo by Win McNamee/Getty Images)

Competitors in action during a qualifying heat for the 12 hour Lawn Mower Endurance Race on September 24, 2011 in Billingshurst, England. First started in 1973 as a motorsport that would be accessible to as many as possible, there is little commercialism or sponsorship, no cash prizes and no modifying of engines. The trophies are donated from various sources with famous names such as Sir Stirling Moss found engraved on the plaques from previous races. (Photo by Matthew Lloyd/Getty Images)

Bryan Berg was introduced to card-stacking by his grandfather at the age of 8. He is a self-taught artist in all of the techniques he uses today. Berg's freestanding card structures are based on a grid-like arrangement, which Berg tested in a structural engineering lab to support 660 lbs per square foot―using no tape, no glue, no folding, and no tricks.

Skoda caused a huge stir with its car made out of cake. The advert features an army of bakers creating a Fabia out of an array of tasty baked treats, while Julie Andrews sings about her favourite things in the background. The chassis is built from huge slabs of sponge cake. Its paintwork is marzipan. Golden Syrup lubricates the engine. And the roof is finished with sugar.

A three metre lego turbine is displayed at Customs House August 16, 2007 in Sydney, Australia. Engineers without Borders are constructing a 7,000 LEGO brick fully functioning three-metre tall wind turbine in Customs House Square as part of a three day technology extravaganza to highlight the organisation's work in developing countries. (Photo by Cameron Spencer/Getty Images)

The Burney, a new streamlined car on the London streets, designed by Sir Denniston Burney who was responsible for the design of the R100 (R 100) airship. The engine is in the rear. (Photo by Topical Press Agency/Getty Images). 15th September 1930

A driver steers a lorry laden with bags of plastic bottles across a recycling yard at the outskirts of Beijing, China, August 19, 2016. As authorities try to control Beijing's burgeoning population and capitalize on skyrocketing land prices, scrap collectors say they are being pushed out despite playing a vital role in China's unique recycling ecosystem. (Photo by Thomas Peter/Reuters)