Why is The Sky Blue?

Summary

The video explores the question of why the sky is blue, addressing a common misconception that it reflects the ocean. Instead, it explains the phenomenon of Rayleigh scattering, where shorter wavelengths of light like blue are scattered by air particles, making the sky appear blue. The video also touches on why the sky appears red during sunsets due to the angle of sunlight. With insights from historical scientists like Leonardo da Vinci and Sir Rayleigh, the video simplifies complex scientific concepts, making them accessible and engaging.

Takeaways

• 😀 The song 'Pelangi-pelangi' from kindergarten taught us about the colors of the rainbow, but the sky isn't always as expected in the song.
• 😀 A common myth is that the blue color of the sky is due to it reflecting the color of the ocean, but this is scientifically inaccurate.
• 😀 Scientists like Leonardo da Vinci, John Tyndall, and Sir Rayleigh explored why the sky is blue, with Rayleigh perfecting the scientific explanation.
• 😀 The sky’s color comes from the Earth's atmosphere, which is primarily air consisting of gases like Nitrogen, Oxygen, and particles like dust and water vapor.
• 😀 Sunlight consists of different wavelengths, and when it enters the atmosphere, it breaks into visible light, including red, orange, yellow, green, blue, indigo, and violet.
• 😀 'White light' is made up of all visible colors and can refract through water droplets to create rainbows, but the sky appears blue due to Rayleigh scattering.
• 😀 Rayleigh scattering occurs when shorter wavelengths like blue and purple light are scattered in all directions, whereas longer wavelengths like red and orange pass through more easily.
• 😀 Our eyes perceive blue more dominantly than other colors because it is scattered more and our eyes are more sensitive to it compared to purple light.
• 😀 Despite purple having a shorter wavelength than blue, the sky doesn’t appear purple because our eyes are more sensitive to blue, and sunlight scatters blue with greater energy.
• 😀 The afternoon sky appears reddish because sunlight travels through a thicker atmosphere at that time, causing blue light to scatter more, allowing red and orange light to dominate.

Q & A

Why is the sky blue and not red, yellow, or green?

The sky appears blue because of a phenomenon called Rayleigh scattering. This occurs when light with shorter wavelengths, such as blue, indigo, and purple, is scattered in all directions by the particles in the Earth's atmosphere. Blue light, in particular, is scattered more than other colors, making the sky appear blue.

What is Rayleigh scattering?

Rayleigh scattering is the scattering of light by particles in the atmosphere that are smaller than the wavelength of light. This scattering is more effective at shorter wavelengths, such as blue and violet light, causing those colors to be scattered more widely, resulting in a blue sky.

Does the sky reflect the ocean to appear blue?

No, this is a myth. While the sky may seem to reflect the color of the ocean, it is actually the result of Rayleigh scattering. The ocean appears blue because of similar scattering effects, but the color of the sky itself is not due to the reflection of the ocean.

Why is the sky not purple, despite purple having a shorter wavelength than blue?

The sky does not appear purple because the sun scatters blue light with greater energy than purple light, and our eyes are more sensitive to blue light. Additionally, the violet light is mostly absorbed by the upper atmosphere, which makes the sky appear blue rather than purple.

What happens to sunlight as it travels through the atmosphere?

Sunlight is made up of various colors of light, which together form white light. As sunlight passes through the atmosphere, shorter wavelengths like blue and violet light are scattered in all directions, while longer wavelengths, like red and orange, pass through with minimal scattering.

Why does the sky appear reddish during the afternoon?

The sky appears reddish in the afternoon because the sun is at a lower angle, and sunlight has to travel through a thicker portion of the atmosphere. The blue light is scattered away from the line of sight, and the red and orange wavelengths dominate, giving the sky a reddish hue.

What are the main components of the Earth's atmosphere?

The Earth's atmosphere consists of gases such as nitrogen, oxygen, water vapor, dust, and pollution. These particles play a role in scattering sunlight and giving the sky its color.

Why are we more sensitive to blue light than to other colors?

Humans have cone cells in their retinas that are sensitive to red, green, and blue light. Our eyes are more sensitive to blue light because of the way these cone cells are distributed and how they respond to different wavelengths.

Why does the color of the sky change at different times of the day?

The color of the sky changes throughout the day due to the angle of the sun. At midday, the sky is blue because sunlight passes through a thinner portion of the atmosphere. In the afternoon, the sun is lower, and its light travels through more of the atmosphere, scattering blue light and allowing red and orange light to dominate.

What is the role of water droplets in forming a rainbow?

When sunlight passes through water droplets, it is refracted and split into its constituent colors, forming a rainbow. The refraction of white light by water droplets results in the distinct spectrum of colors that we see in a rainbow.