A woman holds up an umbrella and license plates, one that reads “love”, during violent protests between riot police and demonstrators in the Causeway Bay district of Hong Kong on October 1, 2019. The city observes the National Day holiday to mark the 70th anniversary of communist China's founding Strife-torn Hong Kong on October 1 marked the 70th anniversary of communist China's founding with defiant “Day of Grief” protests and fresh clashes with police as pro-democracy activists ignored a ban and took to the streets across the city. (Photo by Nicolas Asfouri/AFP Photo)

A camel performs during a “dance competition” held during the Pushkar Camel Fair in Pushkar, in the western state of Rajasthan, on November 5, 2019. Thousands of livestock traders from the region come to the traditional camel fair where livestock, mainly camels, are traded. The annual camel and livestock fair is one of the world's largest camel fairs. (Photo by Himanshu Sharma/AFP Photo)

Cubans gather at Havanas Malecon waterfront to watch the fireworks on the eve of the city's 500th anniversary on November 15, 2019, in Havana, Cuba. The fireworks were launched from the opposite side of the Havana bay, at the El Morro fortress and lighthouse complex. (Photo by Sven Creutzmann/Mambo photo/Getty Images)

A Maori warrior prepares to challenge Prince Charles during his welcome to Takanhanga Marae in Kaikoura, New Zealand November 23, 2019. (Photo by Tracey Nearmy/Reuters)

A couple sits on a swing during stormy weather along a beach by the Mediterranean Sea in Gaza City on December 8, 2021. (Photo by Mahmud Hams/AFP Photo)

Members of Pakistan's Christian minority attend a service ahead of Christmas in Lahore, Pakistan, 22 December 2021. Pakistan is a majority Sunni Muslim country and home to four million Christians out of a total population of around 200 million people. (Photo by Rahat Dar/EPA/EFE)

Five year-old Fatima plays as women weave a carpet in a home workshop in Peshawar, Pakistan, January 13, 2022. (Photo by Fayaz Aziz/Reuters)

“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)