A man bundled up for the cold weather carries a dog in his jacket while walking along the waterfront in New Westminster, British Columbia, Tuesday, December 28, 2021. Environment Canada has issued an arctic outflow warning for Metro Vancouver and the south coast with well below normal temperatures forecast for the region. (Photo by Darryl Dyck/The Canadian Press via AP Photo)

Revellers enjoy a night out in central Liverpool, northwest England, on December 30, 2020 before hightened Tier 3 restrictions closing hospitality venues, and bars indoor and outdoor socialising between households are imposed in the city amid surging cases of the novel coronavirus. (Photo by Oli Scarff/AFP 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)

A pheasant stands in snow near Dulverton on January 30, 2012 on Exmoor, England. After unseasonably mild winter weather, some parts of the UK woke to a covering of snow as a cold spell of weather sets in, with forecasters warning temperatures are set to plunge as the week progresses. (Photo by Matt Cardy/Getty Images)

A landmark lion statue of a department store placed a protective mask is seen Wednesday, August 12, 2020, in Tokyo. The Japanese capital confirmed more than 200 new coronavirus cases on Wednesday. (Photo by Eugene Hoshiko/AP Photo)

A taxi driver waits for passengers inside his taxi parked on the side of a deserted road during the first day of the two-day state-imposed lockdown as a preventive measure against the surge in COVID-19 coronavirus cases in Kolkata on August 20, 2020. (Photo by Dibyangshu Sarkar/AFP Photo)

Revellers partied the night away in Leeds, UK on September 5, 2020. Leeds has been added to Public Health England's coronavirus "watchlist" and could be hit with lockdown measures after a rise in coronavirus cases in the city. (Photo by NB Press LTD/The Sun)