A Saudi soldier fires a mortar towards Houthi movement position, at the Saudi border with Yemen April 21, 2015. (Photo by Reuters/Stringer)

A supercell that spawned a tornado earlier makes it was east north of McLean, Texas on April 16, 2015 in Texas, United States. Huge hail, terrifying lighting and giant supercells the size of buildings – these incredible images depict a year in the life of a storm chaser. Shot in 2015 by photographer Mike Olbinski, 40, this series of pictures show both the beautiful and the extreme nature of weather in the United States. (Photo by Mike Olbinski/Barcroft Media)

A worker pauses for a sandwich, resting on a girder during the construction of a skycraper. (Photo by Hulton Archive/Getty Images). Circa 1930

“On 24 July 2010, a stampede at the 2010 Love Parade electronic dance music festival in Duisburg, North Rhine-Westphalia, Germany, caused the death of 21 people. At least 510 more were injured”. – Wikipedia

Photo: Wall art and candles are pictured in the tunnel of the 2010 Loveparade disaster near to where many of the deaths occurred on the first anniversary of the tragedy on July 24, 2011 in Duisburg, Germany. (Photo by Thomas Starke/Getty Images)

A derelict farm house adorns the horizon as it sits in a field in the Lancashire Countryside on January 26, 2012 in Burscough, England. (Photo by Christopher Furlong/Getty Images)

Dancers prepare before a performance in the backstage area of the Buick exhibition during the “Auto China 2014” Beijing International Automotive Exhibition in Beijing on April 21, 2014. Leading automakers have gathered in Beijing for the kickoff of China's biggest car show, but lackluster growth and environmental restrictions in the world's largest car market have thrown uncertainty into the mix. (Photo by AFP Photo)

In this artist's impression supplied by the ESO (European Southern Observatory) on April 25, 2007, the planetary system around the red dwarf, Gliese 581, is pictured showing what astronomers believe is the most earth like planet found outside our solar system to date. Using the ESO 3.6-m telescope in Chile, astronomers have uncovered the planet which could have water running on its surface. The planet orbits the faint star Gliese 581, which is 20.5 light-years away in the constellation Libra. (Photo by ESO via Getty Images)

A man cries in a graveyard during the funeral of Nasser Ali Afglio, a young Libyan rebel killed during battle with government troops loyal to Libyan ruler Moammar Gaddafi April 19, 2011 in Misrata, Libya. The graveyard where Nasser was buried has hundreds of simple concrete graves; many dozens are those that have been killed during the last two months of fighting in the besieged town. Thousands of civilians are trapped in Misrata as fighting continues between Libyan government forces that have surrounded the city and anti-government rebels there. (Photo by Chris Hondros/Getty Images)