Rainbow is a bow or arc of prismatic colors appearing in the heavens opposite the sun and caused by the refraction and reflection of the sun's rays in drops of rain. Rainbows can be observed whenever there are water drops in the air and sunlight shining from behind at a low altitude angle. The most spectacular rainbow displays happen when half the sky is still dark with raining clouds and the observer is at a spot with clear sky in the direction of the sun. Sun gives off light, which we see as 'white light'. But in fact, it isn't actually white at all, it is actually numerous different color wavelengths. The main colors it gives off are red, orange, yellow,
green, blue, indigo and violet. These colors are called the colors of the spectrum.
Rain don not necessarily need to have a rainbow. A rainbow can be formed in the mist of water droplets created by a waterfall. There is even a man who makes rainbows using water sprays on fire-fighting boats. There are five different kinds of Rainbows: 1-primary, 2-secondary 3-spurious or supernumerary bows, 4-fogbow, 5-lunar rainbow. Primary Rainbows can be watched all of the time. These are the normal red to violet arcs that we see after it rains. Secondary Rainbows are the rainbows that are reflected twice inside of
the rain drop. They have the colors reversed and appear next to the primary rainbow. Spurious
or Supernumerary bows are faint color arcs that sometimes seen next to the primary or secondary bow, due to interference. In this picture you can see the supernumerary as the blue hue underneath the bright primary rainbow. Fogbows or white rainbows are pale circles of light that are sometimes seen in clouds and fogbanks. Lunar Rainbows are formed when the moon emits white light that raindrops can refract and reflect into the atmosphere.