Why is the sky blue (and the sun yellow)?

Summary

This script delves into the fascinating science behind the colors we see in the sky. It explains why the sky appears blue due to the scattering of blue light by atmospheric molecules, which are more effective at scattering shorter wavelengths. The script also addresses why the sun looks yellow and sunsets red, illustrating how sunlight's colors change as it passes through the atmosphere. An experiment with a flashlight and milk in water visually demonstrates these concepts. The explanation extends to why clouds appear white, as larger water droplets scatter all colors equally. This educational narrative provides a clear understanding of light scattering and its impact on the colors we perceive in the sky.

Takeaways

• 🌏 The sky appears blue because atmospheric molecules scatter blue light more than other colors due to its shorter wavelength.
• ☀️ The sun appears yellow to us because the blue light is scattered away by the atmosphere, leaving the longer wavelengths like green, yellow, and red.
• 🌅 During sunrise and sunset, sunlight passes through a greater thickness of the atmosphere, which scatters shorter wavelengths like blue and green, leaving the longer red and orange wavelengths to dominate.
• 🌈 White light is composed of seven colors (VIBGYOR), each with different wavelengths, with violet having the shortest and red the longest.
• 🔬 The scattering of light by atmospheric particles is more pronounced for shorter wavelengths like blue, which is why we see the sky as blue.
• 🚫 The sun does not produce much violet light, and our eyes are less sensitive to it, so we don't perceive violet in the scattered light.
• 💧 Clouds appear white because they are made up of water droplets larger than the wavelength of light, which scatter all colors equally, resulting in white light.
• 🧪 An experiment with a flashlight, water, and milk can demonstrate how particles in a liquid scatter light, with milk particles mimicking the scattering effect of the atmosphere.
• 🌌 Without an atmosphere, the sky would appear dark except for the white sun, as there would be no scattering of light in other directions.
• 📉 As sunlight passes through more of the atmosphere (as during sunrise/sunset), shorter wavelengths are scattered away, leaving the longer, less scattered wavelengths like red and orange.
• 🌉 The beauty of sunrise and sunset is partly due to the direct visibility of the sun without the intense scattering of light that makes it uncomfortable to look at during the day.

Q & A

Why does the sky appear blue to us?

The sky appears blue because the molecules in our atmosphere, such as nitrogen and oxygen, scatter blue light more than red light due to its shorter wavelength.

Why does the sun, which is actually white, often look yellow to us?

The sun appears yellow to us because when sunlight passes through the atmosphere, the shorter wavelength blue light is scattered more than the longer wavelength yellow light, leaving a yellowish hue.

What causes the red color during sunrises and sunsets?

During sunrise and sunset, sunlight passes through a longer path in the atmosphere, scattering away shorter wavelengths like blue and green, leaving the longer wavelengths of orange and red to dominate.

Why do we not see violet in the sky, despite it having an even shorter wavelength than blue?

We don't see violet in the sky because the sun doesn't produce much violet light, and our eyes are less sensitive to violet, resulting in indigo and blue wavelengths being more visible.

What is the scattering of light and how does it relate to the color we see?

Scattering of light occurs when light hits a tiny particle and reflects in all directions. The color we see is the same as the color of the light that is scattered by the particle.

How does the white light from the sun get separated into different colors?

White light from the sun is made up of seven colors (VIBGYOR). The different colors are perceived due to the varying wavelengths of light, with violet having the shortest and red the longest.

Why do clouds appear white instead of blue, even though they scatter light?

Clouds appear white because they are made up of water droplets larger than the wavelength of light, which scatter all colors equally, resulting in the appearance of white light.

How does the size of atmospheric particles affect the scattering of light?

Particles smaller than the wavelength of light scatter shorter wavelengths more than longer ones. However, particles larger than the wavelength scatter all colors equally.

What would the sky look like without an atmosphere?

Without an atmosphere, the sky would appear dark everywhere except for the direction of the sun, which would appear white, as there would be no scattering of light.

Can we recreate the effect of atmospheric scattering with a simple experiment?

Yes, the effect can be demonstrated using a flashlight, a tank of water, and some milk. The milk particles represent atmospheric particles, scattering blue light and making the water appear blue.

Why does the light appear dull during sunrise and sunset, compared to midday?

During sunrise and sunset, sunlight travels through a greater portion of the atmosphere, scattering more light away from the observer, resulting in a dimmer appearance.