Participants climb over a wall at the “Tough Mudder” endurance event series in Arnsberg September 6, 2014. Competitors who took part in the endurance event saw themselves having to overcome various military style obstacles. (Photo by Ina Fassbender/Reuters)

A rider holds on as a bull tries to throw him during the Bull Ride Spectacular on the first day of the 2014 Deni Ute Muster at the Play on the Plains Festival grounds on October 3, 2014 in Deniliquin, Australia. (Photo by Mark Kolbe/Getty Images)

A lunar eclipse appears behind a gargoyle atop the old red Dallas County Courthouse early Wednesday morning, October 8, 2014. The moon appears orange or red, the result of sunlight scattering off Earth's atmosphere. This is known as the blood moon. (Photo by Tom Fox/AP Photo/The Dallas Morning News)

A couple dance tango for tourists at Caminito, a touristic hotspot of La Boca neighborhood in Buenos Aires, Argentina, October 15, 2016. (Photo by Enrique Marcarian/Reuters)

People sit near a fully loaded in Madama near the border with Lybia on January 1, 2015. French Defence Minister Jean-Yves Le Drian paid a surprise visit to northern Niger on January 1, to visit a base being built to combat the growing flow of weapons and jihadists from neighbouring Libya. Le Drian travelled from Chad to Madama, a desert outpost about 100 kilometres from Libya, where he saw in the New Year with troops at a French base. Madama is situated on the route used by jihadists and arms smugglers in southern Libya to reach northern Mali and Niger. (Photo by Dominique Faget/AFP Photo)

This time exposure photo provided by the Santa Barbara County Fire Department shows a series of lightning strikes over Santa Barbara, Calif., seen from Stearns Wharf in the city's harbor, Tuesday evening, March 5, 2019. A storm soaking California on Wednesday could trigger mudslides in wildfire burn areas where thousands of residents are under evacuation orders, authorities warned. (Photo by Mike Eliason/Santa Barbara County Fire Department via AP Photo)

Anti-balaka militia originally sprang up to protect the Christian population of the Central African Republic, but now stand accused of human rights abuses themselves. Last month, the African Union branded militia targeting Muslims in Central African Republic as “terrorists” and said they would be treated as enemy combatants, a day after killing a Congolese peacekeeper and amid deepening international frustration at continuing violence in the impoverished and landlocked country. Photo: A female member of the anti-balaka, a Christian militia, patrols with other militiamen outside village of Zawa April 8, 2014. (Photo by Goran Tomasevic/Reuters)

“A dirty thunderstorm (also, Volcanic lightning) is a weather phenomenon that occurs when lightning is produced in a volcanic plume. Dirty thunderstorms have been reported in Chile above the Chaiten Volcano, above Alaska's Mount Augustine volcano, and Iceland's Eyjafjallajökull volcano”.

Photo: A cloud of ash pours from Puyehue volcano in southern Chile, at sunset on June 5, 2011. (Claudio Santana/AFP)