Artist Sonja Hinrichsen started creating patterns in the snow just for fun in the winter of 2009, during an artist residency in the Colorado Rocky Mountains. But she soon she realized that what she was creating could be piece of art.

"I took a pair of snowshoes with me, which I had never had before, mainly because I wanted to be able to hike into areas with deep snow. Somehow, I started walking patterns with my new snowshoes - just out of play, not at all thinking about an art project. Then I took a camera to photograph the patterns [and] this is when it became interesting."

After doing some experimenting, Hinrichsen learned that the patterns showed up as a white or dark line depending on the location of the camera in relation to the sun.

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She was inspired to create even larger pieces. "I suddenly became the pen on an immensely huge canvas: the landscape."

Two years later, she started working with volunteers. "I wanted to share this amazing nature experience while making art with other people - being out there in the snow landscape for hours, walking becomes sort of meditative after a while. And at the same time, all participants became collaborators in this huge art piece that would adorn their domestic landscapes, their own surroundings."

Hinrichsen does not have a predetermined pattern for participants to walk. Instead, she just gives them a little direction. The pieces can take anywhere from a day to three days to create, depending on how much area they cover.

There are many challenges to creating the huge works of art in a natural setting and weather is a "huge factor," according to Hinrichsen.

"If it snows, we can't do it because our work might be filled in with new snow as we are creating it. Dull weather is also a problem, because if there is no sun, there is no contrast and the work is pretty much invisible. The tracks barely show. It would be possible to work in cloudy conditions - although probably not as fun as with blue skies and sunshine, but when I photograph the work, it needs to be clear and sunny."

There is also a risk with pieces that go on for more than a day. "If it snows the night after the first day, we lose an entire day's work."

The snow can be challenging too. "[At] Lake Catamount in 2013, we had really deep snow because it had snowed for 3 days before we started the piece. So, [the snow] was fluffy and we sank in to our knees even with snowshoes. It was hard work and I was very surprised that my volunteers stayed."

But, in the end all of the hard work and challenges are worth it, according to Hinrichsen, when the piece is finished and she is photographing it from an airplane.

To see more of Hinrichsen's work visit her website.