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 singing group The D-Day Darlings take part in the unveiling ceremony of a permanent war memorial, created by artist and writer Fabian Peake, at St Pancras International railway station in London, Britain, November 8, 2018. (Photo by Peter Nicholls/Reuters)

A German rifleman beside the corpse of a French soldier in a trench at Fort Vaux, France, 1916. (Photo by Hulton Archive/Getty Images)

A visitor is reflected in a light installation at Mulberry Lights on Regent Street in London, UK on November 16, 2018. Visitors have fun taking selfies and posing with the colourful light installations. Mulberry Lights is a series of illuminating interactive experiences that celebrate how light, colour, shapes and people come together to create a modern British Christmas. (Photo by Imageplotter/Rex Features/Shutterstock)

A man passes at the displayed art installation “Middle way” by Romanian artist Bogdan Rata in Kiev, Ukraine, Tuesday, November 20, 2018. The monument set on the central Kiev street of Khreshchatyk, at the place of Vladimir Lenin monument which was destroyed in 2013 during the Maidan events. (Photo by Efrem Lukatsky/AP Photo)

Alvine Uva, right, wrestles the winner's sash from the hands of newly-crowned Miss BumBum 2018 Ellen Santana, left after winning the Miss Bumbum Brazil 2018 pageant in Sao Paulo, Brazil on November 5, 2016. (Photo by Splash News and Pictures)

A dog jumps into the air to catch a ball along the beach near the County Kerry village of Rossbeigh, Ireland, February 4, 2018. (Photo by Clodagh Kilcoyne/Reuters)

Fans dressed up in costume await the cast members on the red carpet at the world premiere of the film "The Avengers: Endgame" in Los Angeles, California, April 22, 2019. (Photo by Mario Anzuoni/Reuters)