This technique is called silhouette, it's created by a lot of light from behind the camera is being subjected on the woman. I admire this technique as I love the effect it creates, it outlines the woman while the background is still visually shown.
A fascinating look at Barbie's proportions outlined on a real woman. On a related note, researchers at the University of South Australia scaled up Ken and Barbie to life-size and concluded that the chance of a man having Ken's body shape are one in 50, while the chance of a woman having Barbie's are one in 100,000. Talk about creating unrealistic body image expectations for girls!
"God often uses small matches to light up great torches. No matter how small you feel in this world, He has something big in store for you." [the outline of a woman standing in a field illuminated by a sunrise]