All About Rainbows for Middle School Science

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Rainbows are one of the most fun science topics! Plus, they are a great way to connect light, the electromagnetic spectrum, and the atmosphere!

If you would like a copy of the picture book, you can get it along with the reading passage, flashcards, and comprehension activities at Teachers Pay Teachers.

Rainbows

How Do Rainbows Form?

Rainbows are giant optical illusions. There isn't a leprechaun hiding gold at the end of a rainbow because there is no end of a rainbow. Rainbows are circles of light refracted through raindrops. We only see half of the loop because the Earth blocks the other half. However, if you are on an airplane at just the right time, you might see a circular rainbow.

Rainbows form when sunlight passes through raindrops. Light travels more slowly in a liquid drop of water than the gases of the atmosphere, so as the light enters the raindrop, it refracts. Refraction is the process of light bending as it enters a new medium. You can see refraction when you stick your finger in a glass of water, and it looks different underwater.

The sunlight refracts as it enters the raindrop and reflects off the inside of the droplet. As the light exits the raindrop, it refracts again as it returns from water to the gas of the atmosphere.

Visible light is made up of seven wavelengths. When the wavelengths are combined, we see white light, but each wavelength is a different color. The longest wavelength is red light, and the shortest wavelength is violet light.

As the wavelengths leave the raindrop, the longer wavelengths bend at greater angles. Red light leaves the raindrop at 42 degrees, and violet light leaves at 40 degrees. This is why red is on top of the rainbow, and violet is on the bottom.

You see a rainbow when the rain is in front of you, and the sun is behind you low in the sky. If the sun is too high in the sky, the entire rainbow will appear below the horizon, and you won't see it.

Everyone sees a different rainbow because the refraction and reflection of light create a circle whose center is on the line stretching from the eye of the observer. You are at the center of any rainbow you see.