The orientation of an image has an effect on how the image is interpreted. In most cases we choose one orientation over the other to emphasis some aspect to the scene as we visualize it. Typically, the options are fairly narrow, we can shoot in portrait or landscape.
Portrait mode emphasizes height, landscape emphasizes width or breadth. In some cases, it’s a matter of personal preference, it depends on what we want to convey with the image.
The composition here shows the environment that the road snakes through.
In the portrait orientation, the road becomes the image.
jnicklin photography 