In summer, a mild wind is often found on the shore of a clam river. This is caused due to

Options

A. difference in thermal conductivity of water and soil
B. convection currents
C. conduction between air and the soil
D. radiation from the soil

Explanation

To solve the question regarding the cause of a mild wind found on the shore of a calm river during summer, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Scenario**: In summer, the temperature of the land increases more rapidly than that of the water in the river. This temperature difference is crucial for understanding the wind patterns.

2. **Temperature Effect on Air**: As the land heats up, the air above it also warms up. Warm air is less dense than cool air, so as the temperature of the air over the land increases, its density decreases.

3. **Rising Warm Air**: The warm air over the land begins to rise because it is lighter (less dense). This creates a low-pressure area over the land as the warm air moves upward.

4. **Movement of Cooler Air**: To fill the low-pressure area created by the rising warm air, cooler air from the river (which has not heated up as much) moves in to replace it. This movement of air from the cooler area (the river) to the warmer area (the land) creates a breeze or mild wind.

5. **Convection Currents**: This process of warm air rising and cooler air moving in to replace it is known as convection. The continuous cycle of this air movement creates convection currents, which are responsible for the mild wind felt on the shore of the calm river.

6. **Conclusion**: Therefore, the mild wind found on the shore of a calm river during summer is primarily caused by convection currents resulting from the temperature difference between the land and the water.

### Final Answer:
The mild wind on the shore of a calm river in summer is caused by convection currents.

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