# Why is the sky blue using avogardo's number?

• kealakamu
In summary, scientists initially thought that the blue color of the sky was caused by dust and water particles in the atmosphere, but later realized that the molecules of oxygen and nitrogen were responsible for scattering light. Einstein calculated the formula for this scattering, which also verified Avogadro's number. The molecules are able to scatter light due to their electric dipole moments induced by the electromagnetic field of light waves.
kealakamu
[SOLVED] Why is the sky blue using avogardo's number?

This question was brought up in a physics class, and was never answered for me.

I was wondering if anyone here can tell me, given avogadro's number, why is the sky blue? (including all the messy equations if possible).

I believe Einstein was the first person to figure this one out.

Thanks
from
kealakamu

To reflect the color of your pretty eyes

Nah, honestly, I have no clue.

haha that's sweet, but then that'd make the sky brown

Tyndall and Rayleigh thought that the blue colour of the sky must be due to small particles of dust and droplets of water vapour in the atmosphere. Even today, people sometimes incorrectly say that this is the case. Later scientists realized that if this were true, there would be more variation of sky colour with humidity or haze conditions than was actually observed, so they supposed correctly that the molecules of oxygen and nitrogen in the air are sufficient to account for the scattering. The case was finally settled by Einstein in 1911, who calculated the detailed formula for the scattering of light from molecules; and this was found to be in agreement with experiment. He was even able to use the calculation as a further verification of Avogadro's number when compared with observation. The molecules are able to scatter light because the electromagnetic field of the light waves induces electric dipole moments in the molecules.

## 1. Why is the sky blue?

The sky appears blue due to a phenomenon called Rayleigh scattering. This is when sunlight enters Earth's atmosphere, and the shorter blue wavelengths are scattered more than the longer red wavelengths, making the blue light more visible to our eyes.

## 2. How does Avogadro's number relate to the color of the sky?

Avogadro's number, also known as the Avogadro constant, is a fundamental constant in chemistry that represents the number of particles in one mole of a substance. In the case of the sky's color, the Avogadro constant helps explain the number of air molecules in our atmosphere that contribute to the scattering of blue light.

## 3. What is the significance of Avogadro's number in understanding the sky's color?

Avogadro's number is important in understanding the sky's color because it helps scientists calculate the number of air molecules in the atmosphere and their interaction with light. Without this constant, it would be challenging to explain the phenomenon of Rayleigh scattering that makes the sky appear blue.

## 4. Could the sky be a different color if the number of air molecules changed?

Yes, if the number of air molecules in the atmosphere were to decrease, there would be less Rayleigh scattering, and the sky might appear less blue. Similarly, if the number of air molecules were to increase, there would be more scattering, and the sky might appear bluer.

## 5. How does the color of the sky change throughout the day?

The color of the sky changes throughout the day due to the position of the sun. During sunrise and sunset, the sun's light has to travel a longer distance through the atmosphere, causing more scattering of blue light and giving the sky a reddish-orange hue. As the sun rises higher in the sky, the blue wavelengths become more dominant, making the sky appear blue.

• Other Physics Topics
Replies
23
Views
4K
• Other Physics Topics
Replies
34
Views
6K
• Classical Physics
Replies
21
Views
901
• Introductory Physics Homework Help
Replies
23
Views
3K
• Other Physics Topics
Replies
7
Views
3K
• General Math
Replies
8
Views
332
• Science and Math Textbooks
Replies
3
Views
859
• Introductory Physics Homework Help
Replies
2
Views
620
• Other Physics Topics
Replies
13
Views
3K
• Quantum Physics
Replies
1
Views
330