Families play on the snow-covered slopes at Barnett Demesne Park, Belfast, Northern Ireland (© Stephen Barnes/Alamy)

Common terns sharing a small fish (© Ryzhkov Sergey/Shutterstock)

Cove of Spires in Kenai Fjords National Park, Alaska (© Sekar B/Shutterstock)

Christmas market in the main square of Braşov, Romania (© Alpineguide/Alamy)

African savanna elephants in Addo Elephant National Park, South Africa (© Robert Harding/Alamy)

The village of Benasque, Huesca, Spain (© Miscellaneoustock/Alamy)

Elevated path in Plitvice Lakes National Park, Croatia (© Alessandro Laporta/Offset by Shutterstock)

View of the Washington Monument and the National World War II Memorial with its Pearl Harbor Dedication, Washington, DC (© Olga Bogatyrenko/Shutterstock)

Rocca Calascio in Abruzzo, Italy (© Francesco Russo/eStock Photo)

Bombe code-cracking decryption machine, Bletchley Park, England (© Louis Berk/Alamy)

Sleeping Arctic fox (© Menno Schaefer/Getty Images)

Queen of the Andes plants with the Cordillera Blanca massif in the background, Peru (© Cyril Ruoso/Minden Pictures)

Poinsettia leaf close-up (© Charles Floyd/Alamy)

Gornergrat railway station and the Matterhorn in Zermatt, Switzerland (© coolbiere photograph/Getty Images)

Pine grosbeak (© Peter Lilja/Getty Images)

Bastei Bridge above the Elbe River in Saxon Switzerland National Park, Germany (© Reinhard Schmid/eStock Photo)

Ludwig van Beethoven sculptures and monument at the Münsterplatz, Bonn, Germany (© dpa/Alamy Live News)

Pine cones, Netherlands (© Marcel ter Bekke/Getty Images)

Tre Cime di Lavaredo as seen from the Lavaredo fork, Sexten Dolomites, Italy (© AWL Images/Danita Delimont)

Early morning frost on trees in Mount Siguniang National Park in Sichuan province, China (© Robert Harding World Imagery/Offset by Shutterstock)

Mountain goat kid in western Montana (© Donald M. Jones/Minden Pictures)

Castlerigg Stone Circle near Keswick, Lake District, Cumbria (© Alan Copson/plainpicture)

Holiday lights on Cape Neddick Light in York, Maine (© Walter Bibikow/Alamy)

Banded pipefish near Moalboal, Philippines (© Jenna Szerlag/Alamy)

Northern lights and wild reindeer on the tundra in Norway (© Anton Petrus/Getty Images)

Santa's giant sleigh and mailbox, Ilulissat, Greenland (© Walter Bibikow/Jon Arnold Images Ltd/Alamy)

Nabana no Sato garden at night in Kuwana, Japan (© Zoonar GmbH/Alamy)

Canada lynx in Montana (© Alan and Sandy Carey/Minden Pictures)

Old Town of Lucerne, Switzerland (© Xantana/Getty Images)

Winter in Bryce Canyon National Park, Utah (© Don Paulson/Danita Delimont)

Fireworks during a New Year's Eve celebration in Zaragoza, Spain (© Martina Badini/Shutterstock)