Night recovery is caused by

Options

A. Condensation of water vapours
B. Local rain
C. Capillary movement
D. Both B and C.

Answer

### Step-by-Step Solution:

1. **Understanding Night Recovery**: Night recovery refers to the process by which the soil surface becomes wet during the night without any rainfall. This phenomenon is primarily due to the condensation of water vapor present in the atmosphere.

2. **Cooling of Soil Surface**: At night, the temperature of the soil surface decreases as it radiates heat. This cooling effect is significant because it allows the air near the soil to reach its dew point.

3. **Condensation Process**: When the air cools to the dew point, the water vapor in the air condenses into liquid water droplets. This condensation occurs on the soil surface, forming a thin layer of moisture.

4. **Role of Water Vapors**: The presence of water vapor in the atmosphere is crucial for this process. As the temperature drops, the capacity of the air to hold water vapor decreases, leading to condensation.

5. **Elimination of Other Options**:
- **Local Rain**: The question specifies that night recovery occurs without rain. Therefore, local rain cannot be the cause of night recovery.
- **Capillary Movement**: This refers to the movement of water through soil due to surface tension and does not relate to the process of night recovery, which is specifically about condensation.

6. **Conclusion**: The correct answer to the question "Night recovery is caused by" is **condensation of water vapours**.