Question

Why is the sky blue? The earth is surrounded by an atmosphere.

Answer 1

The sky appears blue because of a phenomenon called Rayleigh scattering. When sunlight passes through Earth's atmosphere, it encounters tiny particles like air molecules. The blue component of sunlight consists of shorter wavelengths and higher frequencies, causing these charged particles to oscillate faster compared to the red component with longer wavelengths and lower frequencies. The faster oscillation leads to a stronger scattering of blue light compared to red light. Since the acceleration of the charged particles is proportional to the square of the frequency, the intensity of scattered light is proportional to the square of this acceleration. As a result, blue light is scattered almost 10 times more efficiently than red light.

In simpler terms, the blue light in sunlight gets scattered by the particles in the atmosphere, causing the sky to appear blue to our eyes. This is due to the shorter wavelengths and higher frequencies of blue light, which make it interact more strongly with the air molecules in the atmosphere.

The sky appears blue because of a phenomenon called Rayleigh scattering. When sunlight enters the Earth's atmosphere, it contains different colors or wavelengths of light, including red, orange, yellow, green, blue, and violet. Each color corresponds to a different wavelength, with blue light having a shorter wavelength compared to red light.

The Earth's atmosphere is made up of tiny particles, such as molecules and small dust particles. These particles are much smaller than the wavelength of visible light. When sunlight interacts with these particles, it causes them to scatter or change direction. The scattering of light depends on the wavelength of light and the size of the particles.

In the case of the sky, the shorter wavelength of blue light causes it to scatter more than the longer wavelength of red light. This means that when sunlight passes through the atmosphere, the blue light is scattered in all directions, including towards our eyes. As a result, we perceive the sky as blue.

In contrast, red light is scattered less by the particles in the atmosphere, which is why the sun appears more reddish during sunrise or sunset. The longer path of sunlight through the atmosphere at these times allows more of the blue and green light to be scattered away, leaving primarily the red and orange colors to reach our eyes.

So, in summary, the sky appears blue because of the scattering of shorter-wavelength blue light by the particles in the Earth's atmosphere. This phenomenon is known as Rayleigh scattering.

Answer 2

The blue component of the spectrum of visible light has shorter wavelengths and higher frequencies than the red component. Thus, as sunlight of all colors passes through air, the blue part causes charged particles to oscillate faster than does the red part. The faster the oscillation, the more scattered light is produced, so blue is scattered more strongly than red. For particles such as air molecules that are much smaller than the wavelengths of visible light the difference is dramatic. The acceleration of the charged particles is proportional to the square of the frequency, and the intensity of scattered light is proportional to the square of this acceleration. Scattered light intensity is therefore proportional to the fourth power of frequency. The result is that blue light is scattered into other directions almost 10 times as efficiently as red light.