Storm chaser Brad Mack from Buena Park California videotapes a rotating supercell storm west of Newcastle, Texas April 9, 2013. Many of the storms in Tornado Alley that were forecast to be severe this week were taken out by a cold front from Canada. Picture taken April 9, 2013. (Photo by Gene Blevins/Reuters)

A young Free Syrian Army fighter holds a rifle in Haresta neighbourhood of Damascus January 16, 2013. (Photo by Goran Tomasevic/Reuters)

An enthusiast dressed as a zombie takes part in the annual Zombie Walk festival in Prague June 1, 2013. (Photo by David W. Cerny/Reuters)

Four men dressed as zombies participate in a Zombie Walk procession in the streets of Paris October 12, 2013. (Photo by Benoit Tessier/Reuters)

Replica of an old traditional Icelandic house from the 1800 with eruption of Iceland's Eyjafjallajökull volcano, 2013. (Photo by Ingólfur Bjargmundsson/Getty Images)

Brad Snead walks past melting ice on the Cook Inlet beach, Saturday, March 26, 2011, in Kenai, Alaska, while looking for agates. (AP Photo/Peninsula Clarion, M. Scott Moon)

Visitors walk past a family of scarecrows during the Scarecrow Festival in Heather, Britain July 29, 2015. The annual event asks residents of Heather to make scarecrows to raise thousands of pounds for local groups and charities. (Photo by Darren Staples/Reuters)

Men eat oranges from a push cart along a road as a vehicle travels past them in Karachi January 22, 2015. (Photo by Akhtar Soomro/Reuters)