The model was backlit by a late afternoon sun in a forest preserve. We waited until the sun was just right and this shot wasn't even planned, it was just a fun shot I tried against the sun and it was serendipitous that it turned out so great. The flash illuminated the model's face as well as a catchlight in the eyes and the backlighting provided a glowing outline to the hair. The shallow DOF provided a nice depth to the shot. Vignette was added in post.