Rainbows appear magical,but there is a simple explanation for their sudden appearence and breathetaking beauty. A rainbow occurs when sunlight is reflected and refracted by the water droplets in the atmosphere. The lower the sun is in the sky, higher the arc of the rainbow will be. When white sunlight passes through rain drops, the rain drops act like tiny prisms. they bend the different colours in white light, so the light spreads out into a band of colours-red,orange,yellow,green,blue,indigo and violet-the colours of the rainbow.