Chinese tourists watch storm clouds moving along the coast towards the city of Sydney, Australia, November 6, 2015. Powerful storms swept across the city on Friday, with the Australian Bureau of Meteorology issuing a warning for severe thunderstorms with large hailstones, heavy rainfall and damaging winds, local media reported. (Photo by David Gray/Reuters)

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)

Shimmering clearest blue and stretching as far as the eye can see, this is one of Iceland's famed crystal ice caves. The giant solid waves look frozen in time but they are slowly moving along as part of the Vatnajokull Glacier – which stretches across eight per cent of the island. The images were captured in February 2014 by British photographer Rob Lott, 49. Photo: A wide view of Rob Lott in the crystal ice cave in the Vatnajokull Glacier, Iceland. (Photo by Rob Lott/Barcroft Media)

A member of a local swimming club holds a Russian national flag as he dives in at the start of a 24-hour swimming marathon near the western Siberian city of Barnaul March 29, 2014. Thirty members of the club will swim in turn during the event, held to mark Crimea becoming part of Russia, local media reported. (Photo by Andrei Kasprishin/Reuters)

These pictures show a five-year-old boy who is already extremely comfortable around alligators. Blaise's dad T-Mike runs the Kliebert Gator Farm, the biggest and oldest in the world and which was started by his grandfather Harvey in 1957. Photo: T-Mike Kliebert and his son Blaise tackle Chinaman a 12 foot alligator in Hammond, Louisiana. (Photo by Barcroft Media)

This picture taken on July 25, 2014 shows people cooling off in a waterpark in Suining, southwest China's Sichuan province. Meteorological departments issued an orange alert for high temperature as a heat wave embraces Sichuan province, with temperature of most area topped 37, local media reported. (Photo by AFP Photo)

Hot lava trickles down from the Stromboli volcano on August 9, 2014 in Aeolian Islands, Italy. Lava flows down the Mount Stromboli off the Sicilian coast in southern Italy. The volcano – at 3,034ft – is one of the most active in Europe and has been erupting continuously since 1932. (Photo by Tom Pfeiffer/Barcroft Media)

A riot policeman punches Greek photojournalist Tatiana Bolari during a demonstration in Athens' Syntagma (Constitution) square October 5, 2011. Police officers attacked several members of the press covering protests, injuring at least two members of the media. (Photo by Yannis Behrakis/Reuters)