In photography, ambience is the mood a photo creates. For instance, a photo of a person sitting on the floor with their head down against a backdrop of muted colors might make the viewer feel sad or lonely. In contrast, a photo capturing a field of bright flowers on a sunny day can evoke happier feelings.
Photoshop lighting effects can play a role in the ambiance of a photo. In either one of these examples, simply tweaking lighting might yield a different emotion.