Australian photographer James Smart's photo, titled "Dirt" is the grand prize winner of the 2015 National Geographic Photo Contest, selected from more than 13,000 entries. The grand prize winner is chosen among the first place winners in each category -- People, Places and Nature. Smart's photo was also a winner in the Nature category.
In the spring, Smart spent 15 days 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 this winning photo of a tornado.
"Driving down a Colorado dirt road, we were lucky enough to be on the west of it, so it was front lit," Smart said. "This really helped to get great detail out of the image and the perfect light for the sky and foreground."
Here is a look at the other winning photos and honorable mentions.