Jack Dykinga / Lightning storm with rainbow over Saguaro cactus (Carnegiea gigantea) near Redrock, Arizona State Trust, Sonoran Desert, Arizona. September 2015. Long exposure with lightning trigger.

Luciano Candisani / Clouds reflected in flooded field at the end of the wet season, Pantanal, Brazil

Niall Benvie,Niall Benvie / Alto cumulus clouds. Angus, Scotland, August 2012.

Jack Dykinga / Cheyenne River Sioux Tribal Park with severe storm clouds at sunset amid vast grassland, South Dakota, USA

Tim Fitzharris / Grassland and cumulus clouds, Wind Cave National Park, South Dakota

Yva Momatiuk & John Eastcott / Grand Teton peak with cumulus clouds, Grand Teton National Park, Wyoming

Yva Momatiuk & John Eastcott / Heavy cumulus clouds gather before storm above sagebrush desert, central Wyoming

Yva Momatiuk & John Eastcott / Adelie Penguin (Pygoscelis adeliae) flapping wings, Holtedahl Bay, Antarctica

Shin Yoshino / Whistling Thorn (Acacia drepanolobium) trees, Masai Mara National Reserve, Kenya

Yva Momatiuk & John Eastcott / Cumulus clouds above the open range, Pryor Mountain, Montana

Yva Momatiuk & John Eastcott / Cirrus and cumulus clouds over mesa, Monument Valley Navajo Tribal Park, Arizona

Gerry Ellis / Cloudy skies over crashing waves, Bathsheba Beach, windward coast of Barbados, Caribbean