Light and shadow appearance can change by different applications of light in a scene. Depth can also be suggested through form with the effects of light and shadow on the subject.
Elements to watch for and study include light source, highlight, form shadow, cast shadow and the area lightened by reflected light.
Light Source. If outdoors in the daylight, the origin of light in a scene would be the sun. There can be more than one light source for a scene.
Highlight. A bright spot or area that appears on something in the scene.
Form Shadow. A shadow that displays the depth and dimension of the form of something in the scene.
Cast Shadow. A shadow that is cast from something onto another surface.
Reflected Light. Light that is reflected off a surface that lightens another surface.
By observing the cast shadow on the ground behind the figure, you can determine that the light source is from the upper left in front of the figure. With this angle of light, the figure is well lit from the front, with shadows that display the form of the face, hands and clothes. Notice the highlights on the face and hands and the area lightened by reflected light at the underside of the sleeve.
The cast shadow in this scene is on the ground to the left in front of the figure, which means the light source is from the top right behind the figure. With the figure being mostly in shadow, the forms are not as noticeable and the figure is darker and more mysterious. Notice the highlights on the right side of the face and the top of the right sleeve, and the underside of the sleeve is lighted by reflected light.