Why Isn't The Sky Purple?

TL;DR

The sky appears blue because higher frequency blue light scatters more in the atmosphere, while violet light does not.

Transcript

If you know the explanation for why the sky's blue, you've heard that sunlight is white light composed of many frequencies and that higher frequency, bluer, light scatters in the air more than lower frequency, redder, light. So, you might ask "why isn't the sky violet, since violet is an even higher frequency than blue?". First off, ultraviolet lig... Read More

Key Insights

• 🩵 Sunlight is composed of different frequencies, and higher frequency blue light scatters more in the atmosphere, leading to the blue appearance of the sky.
• 📤 Ultraviolet light and x-rays are not visible in the sky due to limited production by the sun and atmospheric blocking.
• 🩵 The color violet in the rainbow is actually a dark blue, and pink, purple, and magenta are combinations of light frequencies.

Questions & Answers

Q: Why isn't the sky violet, since violet light has a higher frequency than blue?

Ultraviolet light and x-rays, which have even higher frequencies, are not visible in the sky due to limited production by the sun and atmospheric blocking. Also, the color violet in the rainbow is a dark blue, not purple.

Q: Can single-frequency light create pink or magenta?

No, pink, purple, and magenta can only be created by a combination of various frequencies of light. Single-frequency light, such as from a laser or splitting white light into a rainbow, cannot produce these colors.

Q: Why don't rainbows made from prisms contain colors like pink, purple, or magenta?

Rainbows made from prisms only show colors that can be created by single-frequency light. Pink, purple, and magenta are not single-frequency colors and require a combination of light frequencies to be perceived.

Q: Why does the sky look blue during a sunset?

During a sunset, the sun's light is scattered by air molecules, causing the sun to appear slightly red hot and the sky to appear blue hot. The scattering of light at different angles contributes to the blue appearance.

Summary & Key Takeaways

• Sunlight is white light composed of different frequencies, and higher frequency blue light scatters more in the atmosphere, causing the sky to appear blue.

• Ultraviolet light and x-rays, which are higher frequencies than blue light, are not visible in the sky due to limited production by the sun and atmospheric blocking.

• The color violet in the rainbow is actually a dark blue, and pink, purple, and magenta are not single-frequency colors but a combination of various frequencies of light.