A photo of a tornado in Colorado has been chosen as the grand prize winner of the 2015 National Geographic Photo Contest. Selected from more than 13,000 entries, the photo, titled Dirt, was shot by James Smart of Melbourne, Australia. He spent 15 days in spring 2015 chasing storms with his brother and some friends who are meteorologists.

On the last day, Smart ended up outside of Simla, Colorado, where he shot the winning photo. "The tornado was slowly getting bigger as it picked up the dust and soil from the ground on the farmland," he said. "It wasn't moving very fast, so we kept getting closer as it tracked next to the home as you can see in the image. Driving down a Colorado dirt road, we were lucky enough to be on the west of the tornado, so it was front lit. This really helped to get great detail out of the image and the perfect light for the sky and foreground."

National Geographic Photo Contest 2015
Grand Prize and Nature category winner: Dirt by James Smart. A rare anti-cyclonic tornado tracks in open farm land, narrowly missing a home near Simla, ColoradoJames Smart/National Geographic Photo Contest 2015

For winning the photo competition, Smart has received $10,000 (£6,756) and a trip to National Geographic headquarters in Washington, DC, to participate in the annual National Geographic Photography Seminar in January 2016.

Joel Nsadha of Binghamton, New York, was placed first in the People category for a portrait of a young man on his bicycle in a slum in Uganda. Francisco Mingorance of Andalusia, Spain, won in the Places category for his photo of a marsh in Spain that has been partially destroyed by radioactive waste.

National Geographic Photo Contest 2015
People category winner: At The Play Ground by Joel NsadhaJoel Nsadha/National Geographic Photo Contest 2015
National Geographic Photo Contest 2015
Places category winner: Asteroid by Francisco MingoranceFrancisco Mingorance/National Geographic Photo Contest 2015

Contestants submitted photographs in three categories – People, Places and Nature – through National Geographic's photography community, Your Shot. All of the winning images may be viewed at natgeo.com/photocontest.

The judges awarded honourable mentions to 10 photos, presented here in no particular order:

National Geographic Photo Contest 2015
Surrealist Painting in Nature by Tugo Cheng. "As the largest mountain ranges in Central Asia, Tian-shan ('sky-mountain' in Chinese), has one of the best natural landscapes in the world and is seen by many as a paradise for outdoor adventures. Thanks to the richness of sediments compounded with the power of erosion by rivers flowing down the mountains, the north face of Tian-shan is carved into stunning plateaus and colourful canyons hundreds of metres deep, resulting in this 'surrealist painting'Tugo Cheng/National Geographic Photo Contest 2015
National Geographic Photo Contest 2015
The Game by Simone Monte. Ipanema, Rio de JaneiroSimone Monte/National Geographic Photo Contest 2015
National Geographic Photo Contest 2015
Nothing to Declare by Lars Hübner. "In the countryside in Taiwan, funerals are usually accompanied by local chapels. When a family member dies, their body is kept in the house, or in a tent built specifically for this purpose. After a set period of time, the deceased, accompanied by a funeral procession is buried. Location: Douliu, Taiwan, Taiwan"Lars Hübner/National Geographic Photo Contest 2015
National Geographic Photo Contest 2015
Acrobat of the Air by Alessandra Meniconzi: "Alpine choughs (Pyrrhocorax graculus), mountain-dwelling birds, perform acrobatic displays in the air. I was able to immortalise their impressive flight skills on a windy day"Alessandra Meniconzi/National Geographic Photo Contest 2015
National Geographic Photo Contest 2015
Colourful chaos by Bence Mate. "White-fronted bee-eaters getting together on a bough before going to sleep in their burrows scraped into a sand wall. I was working on this theme for 18 days, as there were only 5-10 minutes a day, when the light conditions were appropriate. 90% of my attempts did not succeed. I used flash lights to light only the ones sitting on the branch, and not the others, flying above. When in the right angle, the backlight generated rainbow colouring through the wings of the flying birds. Location: Mkuze, KwaZulu-Natal, South Africa"Bence Mate/National Geographic Photo Contest 2015
National Geographic Photo Contest 2015
Changing Shifts by Mohammed Yousef. "As the cubs of a cheetah called Malaika became old enough to start hunting, they moved from one hill to another scanning the lands. Here, they seemed to change shifts as one cheetah leaves the hill while the other takes her place. Location: Masai Mara, Rift Valley, Kenya"Mohammed Yousef/National Geographic Photo Contest 2015
National Geographic Photo Contest 2015
Orangutan in The Rain by Andrew Suryono. "I was taking pictures of some orangutans in Bali and then it started to rain. Just before I put my camera away, I saw this orangutan took a taro leaf and put it on top on his head to protect himself from the rain! I immediately used my DSLR and telephoto lens to preserve this spontaneous magic moment."Andrew Suryono/National Geographic Photo Contest 2015
National Geographic Photo Contest 2015
Overlooking Iraq from Iran by Yanan Li. "There are relics left along the Iran-Iraq borders. A group of Iranian female students play around an abandoned tank. Among them, one girl stands on the tank with her arms open. Location: Shalamcheh, Khuzestan, Iran"Yanan Li/National Geographic Photo Contest 2015
National Geographic Photo Contest 2015
From Generation to Generation by Jackson Hung: "This photo was taken during Chinese New Year's Eve of 2015 in Taiwan. While paying respects to our ancestors, I noticed how the light was coming into the room and saw the passing of incense sticks to each of our family members after sending our prayers. The photo is symbolic since the passing of incense sticks resembles and knowledge and wisdom passed down from generation to generation."Jackson Hung/National Geographic Photo Contest 2015
National Geographic Photo Contest 2015
Hill of Crosses by Hideki Mizuta. "The Hill of Crosses in Šiauliai represents the peaceful resistance of Lithuanian Catholicism to oppression. Standing upon a small hill is the place where many spirits of the dead lives. When I visited this place, a girl in the pink dress ran through as if she brought the peace, hope, love."Hideki Mizuta/National Geographic Photo Contest 2015

See the winners of the 2014 National Geographic Photo Contest.