At 20ºC (68ºF), the saturation mixing ratio is 14 g/kg. You measure a temperature of 20ºC (68ºF) and 10.5 g/kg of water in the air. What is the relative humidity?

To determine the relative humidity, you use the formula that relates the actual mixing ratio to the saturation mixing ratio. Relative humidity is calculated as the actual mixing ratio (the amount of water vapor present in the air) divided by the saturation mixing ratio (the maximum amount of water vapor the air can hold at that temperature), multiplied by 100 to convert it to a percentage.

In this scenario, the saturation mixing ratio at 20ºC is given as 14 g/kg, indicating that at this temperature, the maximum amount of water vapor that air can hold is 14 grams of water per kilogram of air. The actual mixing ratio measured is 10.5 g/kg.

To find the relative humidity, you can set up the calculation:

Relative Humidity = (Actual Mixing Ratio / Saturation Mixing Ratio) × 100

Substituting the values:

Relative Humidity = (10.5 g/kg / 14 g/kg) × 100

Relative Humidity = 0.75 × 100

Relative Humidity = 75%

Thus, the relative humidity is calculated to be 75 percent. This value indicates that the air is holding 75% of the moisture it could hold at that temperature, which explains why this