To determine the correct answer regarding the relative humidity readings from the wet and dry bulb hygrometer over three consecutive days, we need to analyze the data provided and understand how relative humidity is calculated. ### Given Data: - **Dry Bulb Temperatures:** - Day 1: 30°C - Day 2: 29°C - Day 3: 25°C - **Wet Bulb Temperatures:** - Day 1: 22°C - Day 2: 22°C - Day 3: 21°C ### Step-by-Step Explanation: 1. **Understanding Relative Humidity:** Relative humidity (RH) is a measure of the amount of moisture in the air compared to the maximum amount of moisture the air can hold at a given temperature. It is expressed as a percentage. The formula to calculate relative humidity using the dry and wet bulb temperatures is: \[ RH = \left( \frac{E_w}{E_s} \right) \times 100 \] where: - \(E_w\) is the vapor pressure at the wet bulb temperature. - \(E_s\) is the vapor pressure at the dry bulb temperature. 2. **Calculating Vapor Pressures:** The vapor pressure can be estimated using empirical formulas or tables, but for simplicity, we can understand that as the temperature decreases, the maximum capacity of air to hold moisture also decreases, which affects the relative humidity. 3. **Analyzing the Data:** - **Day 1:** - Dry Bulb: 30°C - Wet Bulb: 22°C - The difference between the dry and wet bulb temperatures is 8°C. This indicates a certain level of humidity. - **Day 2:** - Dry Bulb: 29°C - Wet Bulb: 22°C - The difference is now 7°C. The decrease in the dry bulb temperature and the unchanged wet bulb temperature suggests that the air is becoming more humid. - **Day 3:** - Dry Bulb: 25°C - Wet Bulb: 21°C - The difference is 4°C. Again, the decrease in both temperatures indicates an increase in relative humidity. 4. **Conclusion:** - As we move from Day 1 to Day 3, the dry bulb temperature decreases while the wet bulb temperature decreases at a slower rate. This indicates that the air is becoming more saturated with moisture, leading to an increase in relative humidity. ### Evaluating the Options: - **A. Decreased steadily:** This is incorrect because the relative humidity is increasing, not decreasing. - **B. Remained unchanged:** This is also incorrect as the data shows a clear trend of increasing humidity. - **C. Increased steadily:** This is the correct answer. The analysis shows that as the days progress, the relative humidity increases due to the decreasing dry bulb temperature and the relatively stable wet bulb temperature. - **D. Was least on Day 1:** While Day 1 may have the lowest relative humidity compared to the other days, this option does not capture the overall trend of increasing humidity. ### Summary: - Relative humidity is influenced by the difference between dry and wet bulb temperatures. - A decrease in dry bulb temperature with a relatively stable wet bulb temperature indicates increasing humidity. - The correct answer is that the relative humidity increased steadily over the three days. ### Revision Summary: - Relative humidity is calculated using dry and wet bulb temperatures. - A decrease in dry bulb temperature with a stable wet bulb temperature indicates increasing humidity. - The correct answer to the question is that relative humidity increased steadily over the three days. - Always analyze the temperature differences to understand trends in humidity.