Light is obviously important to us artists, as it creates the images we see. If light didn’t bounce off objects and end up hitting our retina, everything would be pitch black, and that wouldn’t be very interesting would it?
Since we can only see light if it enter our eyes, the shape of the object we’re looking at is very important, aswell as the dullness of the surface. A dull object has little bumps that the light can bounce off, whist a shiny object is smooth like a mirror. We can see our reflection in the mirror because the light isn’t scattered around by little bumps, and also because the mirror doesn’t absorb the light. Absorbed light turns into heat, that’s why black surfaces in the sun are hot.
A dull object scatters the light and will look more flat, this is because the light never gets a chance to concentrate. On a shiny object, we can only see the light if the angle of the surface is right, so it’s much more binary. If we look at a shiny sphere floating in space, we will only see the reflection of the sun as a bright dot. If the sphere is dull the reflection will be broken up over a larger surface of the sphere.
Down here on earth, we don’t just have one light source. We have a huge atmosphere, the sky, that scatters light all around. If we’re outdoors during the day, we won’t see any black shadows anywhere. What’s important here is how light can change color after it has bounced off a surface. The color of the surface may absorb some colors and reject others. If light were to hit a pink surface, it would assume that color and transfer it to the next surface. If you put a bush (a green object) next to a white wall and shine a light on the bush, the white wall would receive some of the green light bouncing off the bush.
Light doesn’t just come in one intensity. Our eyes (and cameras) have to crop the light intensity in both ends (bright and dark). this means the statement above about black shadows is sort of false. We might see a shadow as black because our eyes aren’t calibrated to pick up the small amount of light that comes from the shadow. If it’s sunny outside, our eyes tend to calibrate after the brightness, making it harder for us to see details in the shadows. Cameras will most likely capture black shadows a sunny day, this is generally considered undesirable by photographers. The eye is a little better than a camera because it can adjust faster to the lighting conditions and that way pick up shadowed details.
Photographers also dislike cloudy days, because everything will look terribly flat and boring. This is caused by the atmosphere which scatters the light in all sorts of random directions. The result is that surfaces receives an equal amount of light almost regardless of their angle. This makes it harder for us to see the shape and volume of an object.
As light travels through different materials, it gets distorted and bends. A prism, which has a high refractive index, shows how white light (which contains all colors) can be split up into the whole spectrum of color hues. This can also be observed in the atmosphere when the sun sets or rises. Red seems to be the first color to bend around the horizon and hit our eye. Red is better at bending.