## Light and Color

### Tridimensional model

So far, we have been working in the plane, with a cut of a drop and the sun's rays horizontal in the plane coming from the left. This representation was enough to study all the essential aspects, related to what happens to the rays which hit the drop. The transition from this model to a three-dimensional one, of a spherical drop in space, does not offer any difficulties. Just imagine what you get from the flat model, rotating in space, around the horizontal line passing through the center of the drop. For reasons of symmetry, all constructions made in the plane lead to constructions valid in space. The next figure shows the paths of some rays hitting different points on the drop's surface, in a pair of stereoscopic vision for readers who do not need prisms.

In the following interactive application, you can choose the point of impact, the color of the incident ray and the number of rays and analyse the path of those rays in the drop (in mono or in stereo).

The next figure shows on the spherical surface of the horizon, centered on the droplet and partially open, the points corresponding to the directions of the rays of class $$C_{3}$$ and $$C_{4}$$, with the luminous points of the colors corresponding to "each bright direction", highlighting the dark zone between the two regions.

The following interactive application shows, on the spherical surface of the horizon, centered on the droplet and partially open, the points corresponding to each of the ray directions $$C_{1}$$, $$C_{2}$$, $$C_ {3}$$ and $$C_{4}$$.