April Showers Bring…Rainbows?

Rainbows are a natural wonder of the world, often illuminating a band of colors across the sky after a rain shower. Their formation has fascinated people since ancient times, with many theories developed on how various colors of light can align together in one circular arc. Little did some of these early theorists know that it only takes sunlight, water droplets, and the physics of refraction to form this natural wonder.

The Formation of a Rainbow

A rain shower creates millions of tiny water droplets spread throughout the sky. When the sun beams down at a certain angle, its rays of white light interact with these tiny droplets like a prism. This light is composed of the seven wavelengths of light red, orange, yellow, green, blue, indigo, and violet (also referred to as “ROY G. BIV “). As it enters a droplet, the light refracts (bends), reflects off the backside, and refracts again as it exits the water droplet back into the air. Before exiting, however, this white light is broken down into its seven wavelengths of light.

Light Refraction through a Raindrop

Sunlight, or white light, separates into the seven colors of the spectrum when moving through a water droplet. Refraction causes each of these wavelengths of light to bend at a certain angle. For example, the red wavelength bends at an approximate 42 degree angle, while violet bends at an approximate 40 degree angle. With each wavelength bending at an angle between 40 and 42 degrees from millions of water droplets, a colorful arc, known as a rainbow, forms across the sky.

When Can We See Rainbows?

While rainbows are formed most often after a rain shower or in the mist near a waterfall, we only see them when standing in the right location and looking in the right direction. To see a rainbow, a person must be standing with the sun behind them and the rain and rainbow opposite them. Although the science behind rainbows has been solved since ancient times, these natural wonders continue to fascinate people today.

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