“Cracked Earth”

Branching cracks wend through the slopes of Utah in this photograph by Matt Payne. It may seem strange to feature something so dry on a blog about fluid dynamics, but everything seen here depends as much on air and water as on soil, rock, and sand. How water intrudes into the porous landscape and the way it evaporates back out is critical to crack formation. (Image credit: M. Payne; via ILPOTY)