Shadow Art

On satellite imagery and aerial photographs, taken vertically, tall buildings can be recognized as such by their long shadows (if the photographs are not taken in the tropics around noon), while these also show more of the shape of these buildings.
A shadow shows, apart from distortion, the same image as the silhouette when looking at the object from the sun-side, hence the mirror image of the silhouette seen from the other side.
Shadow as a term is often used for any occlusion, not just those with respect to light. For example, a rain shadow is a dry area, which, with respect to the prevailing wind direction, is beyond a mountain range; the range is "blocking" water from crossing the area. An acoustic shadow can be created by terrain as well that will leave spots that can't easily hear sounds from a distance.