Thunderstorm advancing over Bondi Beach in the Eastern suburbs, Sydney, Australia

Durbar Square, Bhaktapur, Kathmandu valley, Nepal. Guardian lions on the steps of a temple. Foggy winter morning November 2005.

Stone lions, Durbar Square, Bhaktapur, Kathmandu valley, Nepal. Foggy winter dawn, november 2005.

A threatening sky contrasting with a blooming field in the Puez-Odle National Park, Dolomites, South Tyrol, Italy, Europe

Whitebacked vulture (Gyps africanus) threat display, Zimanga Game Reserve, KwaZulu-Natal, South Africa, Africa

Dusk beside the Virgin River under a threatening sky in winter, Zion National Park, Utah, United States of America, North America

A cloudy sky over a mountain scene on the Indian Ocean island of Mauritius. Crop of young sugar cane and a lone tree in the foreground.

Twenty Fenchurch Street, The Leadenhall building and the Swiss Re Tower in the City of London from the South bank of the River Thames, UK.

Sunbeams through storm clouds over sailboat

Bush fire at Arnhem Highway at night, Kakadu National Park, Northern Territory, Australia

Thunderstorm and surf in Algajola Bay, North-west coast, Balagne region, Corsica, France, Europe

Cemetery in front of nuclear powerplant, Nitra, western Slovakia, Europe

Thunderstorm Clouds

The Train of Memory, mobile exhibition of Deportation, Grevenbroich Railway Station, Grevenbroich, North Rhine-Westphalia, Germany, Europe

Emissions at dawn from Chrysler's Jefferson North Assembly Plant, Detroit, Michigan, USA

Clouds of a Thunderstorm, Stormy wind clouds over the Peissenberg hill, PŠhl, Bavaria, Germany, BRD, Europe,

Tuomiokirkko Cathedral and Senatintori (Senate Square), Helsinki, Finnland, Scandinavia, Europe

Colosseum, Rome, Lazio, Italy, Europe

The Train of Memory, mobile exhibition of Deportation, Grevenbroich Railway Station, Grevenbroich, North Rhine-Westphalia, Germany, Europe

Threatening clouds above Brodtener Ufer, shore, Baltic Sea spa resort of Travemuende, Bay of Luebeck, Schleswig-Holstein, Germany, Europe, PublicGround

Alpine hut in autumnal mountain landscape with threatening cloudy sky, Pfossental, Merano, Vinschgau, South Tyrol, Italy, Europe

Way cross with alpine hut in autumnal mountain landscape with threatening cloudy sky, Pfossental, Merano, Vinschgau, South Tyrol, Italy, Europe

Way cross with path in autumnal mountain landscape with threatening cloudy sky, Pfossental, Merano, Vinschgau, South Tyrol, Italy, Europe

Menacing cloud front announcing a tropical storm, the Amazon between Manaus and Santarem, Amazonas province, Brazil, South America

Alpine hut in autumnal mountain landscape with threatening cloudy sky, Pfossental, Merano, Vinschgau, South Tyrol, Italy, Europe

Mountain hut on mountain meadow with autumnal mountain forest and threatening cloudy sky, Martell valley, Merano, Vinschgau, South Tyrol, Italy, Europe

Storm over farmland, Carnamah, Western Australia, Australia

Clouds of a Thunderstorm, Stormy wind clouds over the Peissenberg hill, PŠhl, Bavaria, Germany, BRD, Europe,

Point Quobba Lighthouse with big rain cloud in the distance, Western Australia

Wheat field ripe for harvest, grain field, dramatic clouds, thunderclouds

Point Quobba Lighthouse with big rain cloud in the distance, Western Australia

Storm over farmland and Yarra Yarra Lake, Carnamah, Western Australia, Australia

Storm over farmland and Yarra Yarra Lake, Carnamah, Western Australia, Australia

Large turquoise coloured Myrdalsjokull glacier and thunderstorm clouds, Iceland, Europe

Storm over farmland and Yarra Yarra Lake, Carnamah, Western Australia, Australia

The Milky Way and the Northern Lights (Aurora borealis), Finnmark and Troms, Norway, Europe

West coast of Ruegen during a storm, Mecklenburg-Western Pomerania, Germany, Europe

Northern Lights (Aurora borealis), Finnmark, Norway, Europe

Storm over farmland and Yarra Yarra Lake, Carnamah, Western Australia, Australia

High Mountain Rangers Tom Ditola and David Weber are taking a rest on the West Rib on Mount McKinley, Alaska. Mount Hunter in the background. They are above the clouds in blue sky and the sun is shining. Mount McKinley, native name Denali, is the highest mountain peak in North America, with a summit elevation of 20,321 feet (6,194 m) above sea level. At some 18,000 feet (5,500 m), the base-to-peak rise is considered the largest of any mountain situated entirely above sea level. Measured by topographic prominence, it is the third most prominent peak after Mount Everest and Aconcagua. Located in the Alaska Range in the interior of the U.S. state of Alaska, McKinley is the centerpiece of Denali National Park and Preserve. Every climbing season High Mountain Rangers of the Denali National Park Service are called to help climbers in need. If possible the patient is brought down to base camp on foot, only in life threatening conditions a helicopter is called to evacuate the patient to a hospital in Anchorage.

Mountain ranger Brian Scheele on this way to Windy Corner on Mount McKinley, also know as Denali, in Alaska. He is pulling a sled, that together with his heavy backpack is containing all the gear like tents, clothing and food. Every climbing season High Mountain Rangers of the Denali National Park Service are called to help climbers in need. If possible the patient is brought down to Basecamp on foot, only in life threatening conditions a helicopter is called to evacuate the patient to a hospital in Anchorage. Mount McKinley, native name Denali, is the highest mountain peak in North America, with a summit elevation of 20,321 feet (6,194 m) above sea level. At some 18,000 feet (5,500 m), the base-to-peak rise is considered the largest of any mountain situated entirely above sea level. Measured by topographic prominence, it is the third most prominent peak after Mount Everest and Aconcagua. Located in the Alaska Range in the interior of the U.S. state of Alaska, McKinley is the centerpiece of Denali National Park and Preserve.

A mountain ranger is digging out tents after a snowstorm covered them during the night in 14k camp on Mount McKinley, Alaska. Climbers are advised to spare no expense on a expedition-quality tent as it can mean the difference between life and death during a ferocious storm on Denali. Extra poles and repair materials are important in case of damage caused by storms. Plan to take extra pickets, wands or deadmen for tent anchors. Never leave a tent without anchoring it securely. Tents are lost each year due to sudden gusts of wind while the tent was left unattended or drying. Every climbing season High Mountain Rangers of the Denali National Park Service are called to help climbers in need. If possible the patient is brought down to base camp on foot, only in life threatening conditions a helicopter is called to evacuate the patient to a hospital in Anchorage.

Stacks of rocks are placed on a beach for good luck under a threatening sky, Jamaica

Amazing clouds over the landscape of the American mid-west as supercell thunderstorms develop; Nebraska, United States of America

Supercell thunderstorm clouds show off the power of mother nature. Massive clouds build and unleash powerful storms creating a beautiful and awe inspiring spectacle; Colorado, United States of America

A gravel path under dark storm clouds, Highlands scotland

Amazing clouds over the landscape of the American mid-west as supercell thunderstorms develop; Nebraska, United States of America

Church in the countryside of western Iceland with grass fields and rocky landforms, Hellnar, Snaefellsnes, Iceland

Incredible supercell thunderstorm in rural Colorado near the town of Kim. Amazing structure is evident by the strong rotational winds associated with the storm, Kim, Colorado, United States of America

Supercell thunderstorm clouds show off the power of mother nature. Massive clouds build and unleash powerful storms creating a beautiful and awe inspiring spectacle; Colorado, United States of America

Desolate landscape under an ominous sky in Western Mongolia, near Uureg Lake, Mongolia

Incredible supercell thunderstorm in rural Colorado near the town of Kim. Amazing structure is evident by the strong rotational winds associated with the storm, Kim, Colorado, United States of America

A developing severe thunderstorm with large hail crosses the highway in Colorado, near Burlington; Colorado, United States of America

Amazing clouds over the landscape of the American mid-west as supercell thunderstorms develop; Nebraska, United States of America

Lightning bolt strikes from a thunderstorm while a lonely road leads into the storm, Kansas, United States of America

Supercell thunderstorm clouds show off the power of mother nature. Massive clouds build and unleash powerful storms creating a beautiful and awe inspiring spectacle; Colorado, United States of America

Supercell thunderstorm clouds show off the power of mother nature. Massive clouds build and unleash powerful storms creating a beautiful and awe inspiring spectacle; Colorado, United States of America

Wooden steps leading to the beach under dark storm clouds, Druridge bay northumberland england

Wooden posts in a row in the shallow water along the coast under dark storm clouds, St. mary's bay northumberland england

Dark storm clouds over the ocean with waves rolling into the shore, Druridge bay northumberland england

A bench at the water's edge with a dark stormy sky, Moray firth scotland

Pueblo church archway under stormy sky, Picuris Pueblo, New Mexico, United States

Single bare tree with grey sky

Clouds

Clouds and blue sky

Clouds and blue sky

Clouds

Clouds

Commercial jet in cloudy sky

Storm clouds

Commercial jet in cloudy sky

Commercial jet in cloudy sky

View of clouds from airplane

Clouds

Clouds

Western Utah USA

Clouds

Clouds and blue sky

Clouds

Gathering storm clouds

Clouds and blue sky

Sunset behind clouds

Clouds

Clouds

Clouds

Two young girls dressed in white veils and black abaya, the older one threatens the younger one with a stick while the latter is dancing in defiance. In the late afternoon, children from a small village come to play on the white sand beach and turquoise sea on the east coast of Zanzibar, Tanzania.

Male and young ostrich in savanna, Etosha Namibia

Falkland Skua or Brown Skua (Stercorarius antarcticus, exact taxonomy is under dispute). They are the great skuas of the southern polar and subpolar region. South America, Falkland Islands, January

Griffon vulture (Gyps fulvus) displaying, Spain

View of Brecon Beacons National Park and storm clouds in sky at Wales, UK

View of Coast and Highlands National Park of Canada in Cape Breton Island, Canada