Chapter U3.18, Problem 10E

Interpretation Introduction

Interpretation :

Whether one feels cooler at 100 % humidity at 30°C or at 50 % humidity at 30°C must be explained.

Concept Introduction :

Lesser the relative humidity, greater is the water evaporation rate.

Answer to Problem 10E

One will feel cooler at 50 % humidity at 30°C as compared to 100 % humidity at 30°C.

Explanation of Solution

When the relative humidity is only 50 % air still has capacity to hold water vapor. So water is evaporated from our body as sweat. The latent heat of evaporation is taken from our body and it becomes cooler. But if relative humidity is 100 % then the air is saturated with water vapor and can’t hold more vapor at that temperature. So easily, the sweat from our body will not be evaporated.

Conclusion

Thus, one will feel cooler at 50 % humidity at 30°C as compared to 100 % humidity at 30°C as rate of evaporation of sweat is possible in case of 50 % humidity.