Police officers detain a woman who laid flowers for Alexei Navalny at the Memorial to Victims of Political Repression in St. Petersburg, Russia on Friday, February 16, 2024. Russian authorities say that Alexei Navalny, the fiercest foe of Russian President Vladimir Putin who crusaded against official corruption and staged massive anti-Kremlin protests, died in prison. He was 47. (Photo by AP Photo)

“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)

“The Mikoyan MiG-31 (NATO reporting name: Foxhound) is a supersonic interceptor aircraft developed to replace the MiG-25 “Foxbat”. The MiG-31 was designed by the Mikoyan design bureau based on the MiG-25”. – Wikipedia

Photos: The Mikoyan MiG-31 “Foxhound”. Russia, April 2012. (Photo by Alexandr Pak; Source: LiveJournal)

Drinking from a helmet at a graduation ceremony held by the Military University of the Russian Defence Ministry at Moscow's Victory Park in Moscow, Russia on June 15, 2019. (Photo by Gavriil Grigorov/TASS)

Sumo wrestlers in their women's match at the 2021 Russian Sumo Championship at Ak Bars Wrestling Palace in Kazan, Russia on February 14, 2021. There are over 6,000 sumo wrestlers in Russia. (Photo by Yegor Aleyev/TASS)

A portrait of a young woman who died during a Russian attack is pictured with flowers next to her fresh grave in the cemetery of in Mykolaiv, southern Ukraine, on March 21, 2022. (Photo by Bulent Kilic/AFP Photo)

Demonstrators dance around a burning an effigy of the Russian President Vladimir Putin during an anti-war action in Tbilisi, Georgia, Sunday, March 27, 2022. (Photo by AP Photo/Stringer)