The blue colour of sky can be explained on the basis of

Options

A. reflection of light
B. refraction of light
C. dispersion of light
D. scattering of light

Explanation

To explain why the sky appears blue, we can break down the explanation into a series of logical steps:

### Step-by-Step Solution:

1. **Understanding the Phenomenon**: The question asks why the sky appears blue. This is a common observation and can be explained through the behavior of light in the atmosphere.

2. **Identifying the Relevant Concept**: We need to determine which optical phenomenon explains the blue color of the sky. The options given are reflection, refraction, dispersion, and scattering.

3. **Analyzing the Options**:
- **Reflection**: This involves light bouncing off surfaces. It does not explain the color of the sky.
- **Refraction**: This is the bending of light as it passes through different mediums. While it can create optical effects, it does not explain the sky's color.
- **Dispersion**: This is the separation of light into its constituent colors, like a prism. It does not directly explain the blue sky.
- **Scattering**: This is the process where light is redirected in various directions when it strikes small particles in the atmosphere.

4. **Focusing on Scattering**: The blue color of the sky can be explained by Rayleigh scattering, which states that shorter wavelengths of light (blue and violet) are scattered more than longer wavelengths (red and yellow).

5. **Understanding Wavelengths**: The intensity of scattered light is inversely proportional to the fourth power of its wavelength (λ). This means that shorter wavelengths (like blue) scatter more effectively than longer wavelengths (like red).

6. **Conclusion**: Since blue light has a shorter wavelength compared to red light, it is scattered more in all directions by the molecules in the atmosphere. This scattering of shorter wavelengths is why we perceive the sky as blue.

### Final Answer:
The blue color of the sky can be explained on the basis of scattering of light.

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