Due to which phenomenon, advanced sunrise and delayed sunset occur ?

Explanation

**Step-by-Step Solution:**

1. **Understanding the Concepts of Sunrise and Sunset:**
- Sunrise occurs when the sun's rays first reach the observer's eye, while sunset occurs when the sun's rays no longer reach the observer's eye.

2. **The Role of the Atmosphere:**
- The Earth is surrounded by an atmosphere that has varying densities. This atmosphere bends (refracts) the light rays coming from the sun.

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