A Polisario fighter sits on a rock at a forward base on the outskirts of Tifariti, Western Sahara, September 9, 2016. At a rocky outpost in Western Sahara, a new generation of soldiers who have never known war are mobilising as tensions resurface in one of Africa's oldest disputes after a quarter century of uneasy peace. (Photo by Zohra Bensemra/Reuters)

A masked Palestinian uses a board to protect himself during clashes with Israeli forces which occurred shortly before Palestinian leader Mahmoud Abbas' speech to the the United Nations General Assembly, on September 23, 2011 in Qalandia, West Bank. (Photo by Ilia Yefimovich/Getty Images)

General view of the stands in the Atrium during the Big Fashion Wardrobe Spring/Summer fashion and beauty event at Westfield London shopping centre on March 29, 2011 in London, United Kingdom.

General Augusto Pinochet, the President of Chile, with the Argentinian President, Maria Estela Martinez De Peron, at a dinner given in his honour in Buenos Aires. (Photo by Keystone/Getty Images). 22nd April 1975

General view of atmosphere of fans at the “Harry Potter And The Deathly Hallows: Part 2 An IMAX Experience” release party at AMC Loews Kips Bay 15 theater on July 14, 2011 in New York City. (Photo by Rob Kim/Getty Images)

Aerial acrobat Schindler, notorious for his foolhardy stunts, practising one of his tricks listing out of the vertical, from a Klemp plane piloted by Richard Perlia. (Photo by General Photographic Agency/Getty Images). Circa 1927

Penitentes, or nieves penitentes (Spanish for “penitent-shaped snows”), are a snow formation found at high altitudes. They take the form of tall thin blades of hardened snow or ice, closely spaced with the blades oriented towards the general direction of the sun.

Russian President Vladimir Putin, center, uses a binocular, as Defense Minister Sergei Shoigu, left, and chief of Russia's military's General Staff Valery Gerasimov, right, observe military exercises near the Baikal Lake on Wednesday, July 17, 2013. (Photo by Alexei Nikolsky/AP Photo/RIA Novosti/Presidential Press Service)