Contre-jour, French for 'against daylight', refers to photographs taken when the camera is pointing directly toward the source of light. An alternative term is backlighting.

Contre-jour produces backlighting of the subject. This effect usually hides details, causes a stronger contrast between light and dark, creates silhouettes and emphasizes lines and shapes. The sun, or other light source, is often seen as either a bright spot or as a strong glare behind the subject. Fill light may be used to illuminate the side of the subject facing toward the camera. Silhouetting occurs when there is a lighting ratio of 16:1 or more; at lower ratios such as 8:1 the result is instead called low-key lighting.

http://en.wikipedia.org/wiki/Contre-jour