What Is Rainbow Order Of Colors?

What is the order of colors in a rainbow?

From outside to inside, the rainbow shows red, orange, yellow, green, blue, indigo, and violet. The mnemonic ROYGBIV (Roy G. Biv) helps remember the order. Red appears on the outside of the arc, with a viewing angle of about 42 degrees from the antisolar point (the point directly opposite the sun from your perspective). Violet appears on the inside at about 40 degrees. The other colors fall between these, blending smoothly rather than appearing as sharp bands. Sometimes a fainter secondary rainbow appears outside the primary, with colors reversed.

Why are colors in this specific order?

The order results from how different wavelengths of light refract (bend) when passing through water droplets. Each color has a different wavelength, with red around 700 nanometers and violet around 400 nanometers. The refractive index of water is slightly different for different wavelengths, causing shorter wavelengths (blue and violet) to bend more than longer wavelengths (red and orange). This wavelength-dependent bending, called dispersion, separates white sunlight into its component colors with red emerging at one angle and violet at another.

Is indigo actually a distinct color?

Indigo's inclusion in the rainbow is somewhat debatable. Isaac Newton, who first systematically described the spectrum, included seven colors partly to match the seven notes of the musical scale (he was influenced by aesthetic and numerical symmetry). Modern color scientists often describe only six distinct colors in a rainbow, omitting indigo as a transitional shade between blue and violet rather than a separate color. The human eye perceives a continuous spectrum, not seven discrete bands, so the exact number is more a matter of convention than physics.

How do rainbows form?

Rainbows form when sunlight enters water droplets in the air, refracts as it enters, reflects off the back of the droplet, and refracts again as it exits. The two refractions split the white light into its constituent colors, while the reflection sends the colored light back toward the observer at specific angles. Because each color exits at a slightly different angle, the colors form an arc with the sun behind the observer. Rainbows are always opposite the sun, which is why you can only see them when sunlight is shining from behind you and rain is falling in front of you.