What is the Humidity Ratio when the Dry Bulb Temperature is 100°F and the Relative Humidity is 60%?

To determine the humidity ratio in grains per pound of dry air when given a dry bulb temperature of 100°F and a relative humidity of 60%, we need to reference psychrometric principles. The humidity ratio is a measure of the actual moisture content of the air relative to the dry air.

At a dry bulb temperature of 100°F and a relative humidity of 60%, we can use a psychrometric chart or appropriate formulas to calculate the moisture content. The values indicate that at these conditions, the air can hold a certain amount of water vapor.

Given that 100°F and 60% relative humidity corresponds to a humidity ratio of 176 grains per pound of dry air, this number represents the actual weight of water vapor present in that pound of dry air. A humidity ratio of 176 grains indicates that this air mixture is relatively moist, aligned with the provided conditions.

Thus, the calculated value accurately reflects the conditions described in the question, making it the correct choice in this scenario.