The rainbow is an atmospheric phenomenon. It appears in the sky to or after a rain, it can be seen near falls or over splashes at a fountain. It looks differently - happens an arch, sometimes in the form of a circle or splashes. That after a rain there was a rainbow, sunlight is necessary.
Imagine that the rainbow is a one ray of sunlight. Usually sunshine are invisible as they dissipate air. Day sunlight often is called white. Actually, a feeling of white light is caused by mixing of such flowers as red, orange, yellow, green, blue, blue and violet. This combination of flowers is called a solar range, their set also gives white color.
Green foliage, the blue sky, bright paints of the nature - all this refraction of sunshine which passing through a thin layer of the atmosphere reflect components of white color.
The concept about spectral structure of white color was entered by Isaac Newton. He made experiment when the beam from a light source was passed through a narrow crack behind which the lens is placed. From it the beam of light was redirected on a prism where refracted and broke up to components. Remember that the prism is a polyhedron with the basis which parties form a volume figure. The drop of water is the real prism. Getting through it, the beam of the sun refracts and turns into a rainbow. Sunlight differently because each wave of a range has the length is split. Distinctive feature is also that two nearby standing the observer will see everyone the rainbow. The effect will occur because drops cannot be identical, and the arrangement of flowers, their brightness, width of arches of a rainbow directly depend on the size and a form of drops. If you want to see a rainbow in all beauty, it is necessary that the sun shone you in a back. The rainbow will be brighter also nasyshchenny if light refracts through large drops if they small, are wider than an arch, but their color less bright. Happens so that when falling a drop of a rain become flattened, in this case the radius of a rainbow will be small. If drops when falling are extended, then, the rainbow will be high, but its colors pale.