A couple kisses in a central Barcelona street during the first night without the state of alarm, on 9 May, 2021 in Barcelona, Catalonia, Spain. The state of alarm that the Government decreed for the second time six months ago ended at 00.00 hours this Sunday, May 9. In Catalonia this has led to the fall of the curfew and the perimeter confinement of the Community. (Photo By Lorena Sopena 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)

In this timed-exposure night photo taken early on February 12, 2017, Mount Sinabung volcano spews reddish smoke and ash, as seen from the Karo district in North Sumatra province. Activity levels have increased in the past week, with Sinabung shooting hot ash clouds into the sky dozens of times, according to the local volcano monitoring agency. (Photo by AFP Photo/Stringer)

The body of one of several U.S. soldiers who were executed after being captured by North Korean troops just south of Seoul in early July 1950. (Photo by AP Photo)

While much of the U.S. sustains another round of winter weather, a brown anole, a species of lizard, finds a blooming poinsettia the perfect perch to catch some afternoon rays of sunshine in a Maitland, Fla., neighborhood, Monday, January 8, 2024. After a cold front brings storms to Central Florida on Tuesday, rain returns to the forecast on Friday with temperatures near 80 predicted. (Photo by Joe Burbank/Orlando Sentinel via AP Photo)

A boy jumps from a swing during sunset in Valras-Plage, southern France December 29, 2014. (Photo by Yves Herman/Reuters)

A girl goes to school just before sunrise in Frankfurt, Germany, Wednesday, December 11, 2019. (Photo by Michael Probst/AP Photo)

A surfer takes some air off a wave while surfing after sunset in Cardiff, California, U.S., January 7, 2020. (Photo by Mike Blake/Reuters)