Mixing Ratio Relative Humidity Calculator Wet Bulb Dry Bulb

Psychrometric Equation:

\[ w = \frac{C_p (T_w - T_d) + L_v (e_s(T_w) - e(T_d))}{L_v} \]

Specific Heat Capacity (Cp):

J/kg·K

Wet Bulb Temperature (Tw):

°C

Dry Bulb Temperature (Td):

°C

Latent Heat of Vaporization (Lv):

J/kg

Atmospheric Pressure:

Mixing Ratio (w):

Relative Humidity (RH):

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1. What is the Psychrometric Equation?

The psychrometric equation relates the mixing ratio and relative humidity to wet bulb and dry bulb temperatures, specific heat capacity, and latent heat of vaporization. It's fundamental in meteorology and HVAC calculations.

2. How Does the Calculator Work?

The calculator uses the psychrometric equation:

\[ w = \frac{C_p (T_w - T_d) + L_v (e_s(T_w) - e(T_d))}{L_v} \]

Where:

\( w \) — Mixing ratio (kg/kg)
\( C_p \) — Specific heat capacity of air (J/kg·K)
\( T_w \) — Wet bulb temperature (°C)
\( T_d \) — Dry bulb temperature (°C)
\( L_v \) — Latent heat of vaporization (J/kg)
\( e_s(T_w) \) — Saturation vapor pressure at Tw (Pa)
\( e(T_d) \) — Actual vapor pressure at Td (Pa)

Explanation: The equation balances the heat and moisture transfer between air and a wet surface to determine humidity parameters.

3. Importance of Mixing Ratio and RH

Details: Mixing ratio is the mass of water vapor per unit mass of dry air, while relative humidity indicates how close the air is to saturation. Both are crucial for weather forecasting, comfort analysis, and industrial processes.

4. Using the Calculator

Tips: Enter all required parameters with proper units. Default values are provided for Cp (1005 J/kg·K) and Lv (2454000 J/kg) which are standard for air and water respectively.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between wet bulb and dry bulb temperatures?
A: Dry bulb is the ambient air temperature, while wet bulb is the lowest temperature achievable by evaporative cooling.

Q2: Why is mixing ratio important?
A: Mixing ratio is conserved in adiabatic processes, making it useful for tracking air parcels in meteorology.

Q3: What are typical values for mixing ratio?
A: In Earth's atmosphere, mixing ratio typically ranges from 0.001 kg/kg in dry areas to 0.025 kg/kg in humid tropical regions.

Q4: How accurate is this calculation?
A: The calculation provides good estimates for standard atmospheric conditions but may have errors in extreme temperatures or pressures.

Q5: Can I use this for high-altitude calculations?
A: For high altitudes, you should adjust the atmospheric pressure parameter to match your elevation.