What is a Mixing Ratio Calculator

Mixing Ratio Calculator computes the actual mixing ratio, saturation mixing ratio, and relative humidity of air based on temperature and pressure data.

It is widely used in meteorology to assess atmospheric moisture content and humidity levels.

How to Calculate Mixing Ratios

Input air temperature, dew point, and station pressure with their units. The formulas are:

• Actual Vapor Pressure (e): \( e = 6.11 \times 10^{\frac{7.5 \cdot T_{dew\ point}}{237.7 + T_{dew\ point}}} \) (hPa)
• Saturated Vapor Pressure (e_s): \( e_s = 6.11 \times 10^{\frac{7.5 \cdot T_{air}}{237.7 + T_{air}}} \) (hPa)
• Actual Mixing Ratio (w): \( w = 621.97 \times \frac{e}{P_{station} - e} \) (g/kg)
• Saturation Mixing Ratio (w_s): \( w_s = 621.97 \times \frac{e_s}{P_{station} - e_s} \) (g/kg)
• Relative Humidity (RH): \( RH = \frac{w}{w_s} \times 100 \) (%)

Submit the form to calculate the results.

Examples

Example 1: Air Temp = 25°C, Dew Point = 15°C, Station Pressure = 1013.25 hPa.

Calculation: \( e = 6.11 \times 10^{\frac{7.5 \cdot 15}{237.7 + 15}} \approx 17.04 \, \text{hPa} \), \( e_s = 6.11 \times 10^{\frac{7.5 \cdot 25}{237.7 + 25}} \approx 31.67 \, \text{hPa} \), \( w = 621.97 \times \frac{17.04}{1013.25 - 17.04} \approx 10.62 \, \text{g/kg} \), \( w_s = 621.97 \times \frac{31.67}{1013.25 - 31.67} \approx 19.83 \, \text{g/kg} \), \( RH = \frac{10.62}{19.83} \times 100 \approx 53.55\% \)

Example 2 (Custom Units): Air Temp = 77°F (25°C), Dew Point = 59°F (15°C), Station Pressure = 29.92 inHg (1013.25 hPa).

Results match Example 1 after unit conversion.

Enter values to verify.

Frequently Asked Questions (FAQs)

1. What is the mixing ratio?

The mixing ratio is the mass of water vapor per unit mass of dry air (g/kg), with actual and saturation versions indicating current and maximum moisture capacity.

2. Why must dew point be less than air temperature?

Dew point below air temperature ensures the air is not saturated; if equal, relative humidity would be 100%.

3. What units are used for pressure?

Input can be in mb, bar, psi, atm, hPa, kPa, inHg, or mmHg, converted to hPa for calculation.

4. How is relative humidity calculated?

It’s the ratio of actual to saturation mixing ratio, expressed as a percentage (\( RH = \frac{w}{w_s} \times 100 \)).