Explanation:

When air is heated without changing its moisture content, the dew point remains the same. This is because the dew point is the temperature at which the air becomes saturated with water vapor, causing condensation to occur. The moisture content of the air is determined by the amount of water vapor present, and heating the air does not change the amount of water vapor in it.

Factors Affecting Dew Point:

To understand why the dew point remains the same when air is heated without changing its moisture content, it is important to consider the factors that affect the dew point:

1. Temperature: The dew point is directly related to the temperature of the air. As the temperature decreases, the air can hold less water vapor, leading to condensation and a lower dew point.

2. Humidity: The amount of water vapor present in the air affects the dew point. Higher humidity means more moisture in the air, resulting in a higher dew point.

3. Moisture Content: The moisture content of the air, which is determined by the amount of water vapor present, is a key factor in determining the dew point.

Impact of Heating on Dew Point:

When air is heated without changing its moisture content, the temperature increases but the amount of water vapor remains the same. This means that the relative humidity decreases because the air can now hold more moisture at the higher temperature. However, since the moisture content does not change, the dew point remains the same.

Example:

For example, let's consider a sample of air with a temperature of 20°C and a dew point of 10°C. If we heat this air to 30°C without adding or removing any moisture, the relative humidity will decrease because the air can now hold more water vapor at the higher temperature. However, the dew point remains the same at 10°C because the moisture content has not changed.

Therefore, when air is heated without changing its moisture content, the dew point remains the same.