Secondary school graduates play in a fountain as they celebrate the last day of school, traditionally called the “last bell” in central Kiev, Ukraine on May 31, 2019. (Photo by Valentyn Ogirenko/Reuters)

“Kids of Sapa”. Four little beautiful Hmong girls from Lao Chai Village, near Sapa, Vietnam. (Photo and caption by Felipe Hanower/National Geographic Traveler Photo Contest)

Cooler temperatures begin this week as a polar vortex brings much colder conditions with the chance of snow for Snowdonia, Ogwen Valley, North Wales on 22nd October 2018. The Ogwen Valley and Tryfan Mountain looking splendid in the Autumn sunrise. (Photo by DGDImages/Alamy Live News)

The waning moon sets behind leafless sumac trees on a crisp, clear morning, Thursday, December 15, 2016, in Portland, Maine. Much of the northern Mid-Atlantic and Northeast will stay cold for the next couple of days as the arctic air remains stuck over the northern Appalachians, the National Weather Service said. (Photo by Robert F. Bukaty/AP Photo)

The Pink Floyd inflatable pig floats next to Broadcasting House to promote their new exhibition at the V&A museum, in London, Britain May 10, 2017. (Photo by Neil Hall/Reuters)

A woman takes pictures using her mobile phone on a deserted square decorated ahead of Christmas, in Pristina on December 7, 2020, during a government-imposed curfew from 7pm to 5am, as part of preventive measures against the spread of the Covid-19. (Photo by Armend Nimani/AFP Photo)

Canadian actress Nina Dobrev kicks her leg up at Burning Man in the first decade of September 2022. (Photo by nina/Instagram)

Standalone picture dated June 7th, 2022 shows Flt Lt Adam O’Hare rehearsing in the iconic Typhoon plane over Lincolnshire yesterday (Tues) as he trains for this summers airshows with vapour trails over the wing. The phenomenon is caused by low pressure areas created on the aircraft's skin and wings as it moves through moist air. As the pressure drops so does the temperature, and if the temperature reaches the saturation point, water vapor is created. (Photo by Claire Hartley/Bav Media)