In cold countries, the phenomenon of looming takes place, because refractive index of air decreases with height

Options

A. decreases with height
B. increases with height
C. does not change with height
D. become infinity at the surface

Answer

To solve the question about the phenomenon of looming in cold countries and the relationship between the refractive index of air and height, we can break it down into the following steps:

### Step-by-Step Solution:

1. **Understanding Looming**:
- Looming is an optical phenomenon where objects appear to be elevated above their actual position. This occurs due to the bending of light rays as they pass through layers of air with varying refractive indices.

2. **Refractive Index and Temperature**:
- The refractive index of air is influenced by temperature and humidity. In cold countries, the air is often colder and can contain more water vapor or droplets, which affects the refractive index.

3. **Variation of Refractive Index with Height**:
- As we move up in the atmosphere, the temperature typically decreases, and the density of air changes. The refractive index of air decreases with height because the air becomes less dense at higher altitudes.

4. **Explanation of the Phenomenon**:
- In cold conditions, the lower layers of air may have a higher refractive index due to the presence of water vapor or droplets. As light travels from the colder, denser air to the warmer, less dense air, it bends upwards, causing objects to appear higher than they actually are.

5. **Conclusion**:
- Therefore, the statement that "the refractive index of air decreases with height" is correct and explains why the phenomenon of looming occurs in cold countries.

### Final Answer:
The phenomenon of looming occurs in cold countries because the refractive index of air decreases with height.