Light and Photography

THE MYSTERY OF LIGHT:

Blue and red are two components of light. Blue light has a short wavelength, while the wavelength of red is long. The shorter the wavelength, the stronger the light scattered. (Blue light is strongly scattered.)

During the day, the sky looks blue because of this strong scattering. At dawn and dusk, light passes through the atmosphere for a longer period, which scatters blue light waves. Red and orange, with their longer wavelengths, dominate because they scatter less, which is why the sky looks red early in the day and when the sun is setting

Rainbows:

Rainbows appear in seven colors because water droplets break sunlight into the seven colors of the spectrum. You get the same result when sunlight passes through a prism. The water droplets in the atmosphere act as prisms, though the traces of light are very complex.
When light meets a water droplet, it is refracted at the boundary of air and water, and enters the droplet, where the light is dispersed into the seven colors. The rainbow effect occurs because the light is then reflected inside the droplet and finally refracted out again into the air.

Rainbows: Refraction of the Seven Colors of the Spectrum:

A rainbow has seven colors because water droplets in the atmosphere break sunlight into seven colors. A prism similarly divides light into seven colors. When light leaves one medium and enters another, the light changes its propagation direction and bends. This is called refraction. However, because of differences of refractive index, this refraction angle varies for each color or according to the wavelength of the light. This change of the angle of refraction, or refractive index, in accordance with the wavelength of light is called dispersion. In conventional media, the shorter the wavelength (or the bluer the light), the larger the refractive index.

Water Droplets Reflect Refracted Light:

Sunlight hitting a water droplet (sphere) in the atmosphere will be refracted on the surface of the droplet, and enters the droplet. When the refraction process occurs, the light breaks up into seven colors inside the water droplet, and is next reflected at the other surface of the droplet after traveling inside it. Note that in reflection the angle of reflection is the same as the angle of incidence, which means that reflected light travels in a predetermined path while maintaining the difference of angle of refraction. The light is refracted again when it exits the droplet, further emphasizing the dispersion. The primary reflection of a main rainbow and the secondary reflection from a slightly darker auxiliary rainbow disperse the light into the seven colors our eyes see.