Written By: Marilee Hernandez Edited By: Yosharelli S.
Welcome Young Explorers!
As you stroll down the block, and watch a plane passing by, do you notice the hue of the sky? Why is the sky blue? Why not red or yellow? Questions like these pop up in our brains about everyday phenomenons, such as, the true reason behind the blue sky and the formation of rainbows. Luckily for us, science helps us answer these questions! It shows us how light interacts with our atmosphere to create the most beautiful views. Young explorers, let's dive into the science behind these beautiful phenomena and expand your curiosity!
Why is the Sky Blue?
If you’ve ever looked up to see a passing plane, you notice that the sky is blue. But why is this? The sky is blue because of the way that sunlight interacts with the gases and particles in our atmosphere. The way light travels is known as Rayleigh scattering. Although sunlight seems plainly white, it is composed of an array of colors, each having different wavelengths. Newton discovered that all colors of the rainbow are visible when light hits a glass prism. In rainbows we see the full spectrum of colors such as red, orange, yellow, green, blue, indigo, and violet. In the prism, it breaks the light, illuminating each of the colors individually.
When sunlight enters the Earth, it interacts with molecules in the atmosphere. Through the interactions between molecules smaller than the sunlight’s many wavelengths, lights scatter in all directions. Some of these molecules include oxygen and nitrogen. Shorter wavelengths such as blue light and violet light are scattered more than longer wavelengths such as red light and orange light. Blue light is scattered more because shorter wavelengths can travel faster. Whereas red light and orange light take longer to travel because they have long wavelengths. So since violet light has a shorter wavelength than blue light, why do we see a blue sky and not a violet sky? The sky is blue because our eyes are more sensitive to blue light and the upper atmosphere absorbs a portion of violet light. Ultimately, we see a blue sky because blue light has short wavelengths, we are sensitive to blue light, and the atmosphere absorbs a portion of violet light.
How Do Rainbows Form?
Right after a rainstorm, nothing beats the feeling of gloominess being replaced by a bright sunny afternoon and the magical sight of a rainbow. By any chance, do you know how rainbows form? Well, when the sunlight interacts with the water droplets in the atmosphere, light is bent and bounces inside the droplet. The action of light bouncing makes the beaming spectrum of colors that we so everlasting admire, exist.
When sunlight first enters the droplet, it slows down and begins to bend- a process known as refraction. Due to the different wavelengths, the light bends in different amounts. Red light bends the least and blue light the most. After the light is bent, it reaches the back of the droplet and is reflected inside the droplet. You can envision this process by comparing it to light bouncing off of a mirror. This causes the light to travel to the front of the droplet. When the light exits the droplet it experiences more bending which causes the light to scatter more. This finalizes the formation of the rainbow. A single color in the rainbow is produced by a water droplet. Due to the many droplets, a complete arc of colors is created by each scattered light. Notice that the rainbows always form in a specific order: red, orange, yellow, green, blue, indigo, and violet. Essentially, rainbows form when light is refracted in the droplets in the atmosphere and bent as it exits, causing the spectrum of colors.
Well that concludes today’s lesson young explorers, remember to stay curious and continue asking questions. I’ll see you in our next adventure!
Reference
Henderson, A. (2023). How are rainbows formed? the science behind the colors. Retrieved from https://science.howstuffworks.com/nature/climateweather/atmospheric/question41.htm
Why is the Sky Blue? (2022). Retrieved from https://spaceplace.nasa.gov/blue-sky/en/
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