Umbra Sand

Umbra, penumbra and antumbra

The umbra, penumbra and antumbra are three distinct parts of a shadow, made by any light source after impinging on an opaque object of lesser size. In cases of equal or larger impinging objects, only an umbra and penumbra are generated. Assuming no diffraction, for a collimated beam of light, only the umbra is cast.

Sand

Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is usually defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class of soil or soil type; i.e., a soil containing more than 85 percent sand-sized particles by mass.

Desert sand (color)

Desert sand is a very light and very weakly saturated reddish yellow color which corresponds specifically to the coloration of sand. It may also be regarded as a deep tone of beige.

umbra

Noun

1. The fully shaded inner region of a shadow cast by an opaque object.

sand

Noun

1. Rock that is ground more finely than gravel, but is not as fine as silt (more formally, see grain sizes chart), forming beaches and deserts and also used in construction.

Adjective

1. Of a light beige colour, like that of typical sand.