1. Shadows in the desert

2. Shadow A shadow is a region of darkness where light is blocked. It occupies all of the space behind an opaque object with light in front of it.

4. Opaque What does it mean? Passes no light. What happens to the light energy that strikes an opaque object. It is absorbed & turned into heat or reflected.

5. Transparent The permitting of the passage of radiation without significant deviation or absorption.

6. Translucent The permitting of passage of radiation but not without some scattering or diffusion. (frosted glass)

7. Umbra (Latin: shadow) The umbra is the darkest part of a shadow. From within the umbra, the source of light is completely concealed by the occulting body.

8. Penumbra (Latin: paenes "almost, nearly" + umbra "shadow") Where the light source is only partially concealed. More specifically, the penumbra is the region in which only a portion of the occulting body is obscuring the light source.

10. Seasons and Shadows

13. Earth and Sun Incoming Sun Light AngleSun Angle

14. Seasons Applet Earth and Sun