It's all about abstraction here, isn't it, Kal? She sees what we don't see, so our imaginations are called upon to work overtime. Did a bird just leave its calling card on her umbrella? Is that sun she sees at last? Or is that plane flying too low? We will never know. And there's the value of this image.
What is she looking at?? And why you title it disbelief?? To me she seems more like being curious about something, or being shocked by something. I don't know, but I want to know the story, outside the picture.