Wet Bulb Temperature Calculation

Wet Bulb Temperature Formula:

\[ T_w = \text{Iterative solution: } e = e_s(T_w) - \frac{(e_s(T_d) - e)}{\gamma} \text{ where } \gamma = 0.00066 (1 + 0.00115 T_w) \]

Dry Bulb Temperature (Td):

°C

Saturation Vapor Pressure (es):

hPa

Actual Vapor Pressure (e):

hPa

Wet Bulb Temperature (Tw):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is Wet Bulb Temperature?

Wet bulb temperature is the lowest temperature that can be reached by evaporating water into the air. It represents the temperature read by a thermometer covered in water-soaked cloth, which accounts for both heat and moisture in the air.

2. How Does the Calculator Work?

The calculator uses the psychrometric wet bulb formula:

\[ T_w = \text{Iterative solution: } e = e_s(T_w) - \frac{(e_s(T_d) - e)}{\gamma} \text{ where } \gamma = 0.00066 (1 + 0.00115 T_w) \]

Where:

\( T_w \) — Wet bulb temperature (°C)
\( T_d \) — Dry bulb temperature (°C)
\( e_s \) — Saturation vapor pressure (hPa)
\( e \) — Actual vapor pressure (hPa)
\( \gamma \) — Psychrometric constant (unitless)

Explanation: This iterative equation solves for the wet bulb temperature by balancing the energy and mass transfer equations in psychrometrics.

3. Importance of Wet Bulb Temperature

Details: Wet bulb temperature is crucial for understanding human comfort, heat stress, HVAC design, agricultural applications, and industrial processes involving evaporation and cooling.

4. Using the Calculator

Tips: Enter dry bulb temperature in °C, saturation vapor pressure in hPa, and actual vapor pressure in hPa. All values must be valid and within reasonable atmospheric ranges.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between dry bulb and wet bulb temperature?
A: Dry bulb measures air temperature, while wet bulb measures the cooling effect of evaporation. The difference indicates humidity levels.

Q2: Why is iterative solution needed?
A: The wet bulb equation is implicit - the psychrometric constant depends on the wet bulb temperature itself, requiring iterative methods to solve.

Q3: What are typical wet bulb temperature ranges?
A: Normally ranges from the dew point temperature up to the dry bulb temperature. Values above 35°C are considered extremely dangerous for humans.

Q4: How accurate is this calculation?
A: Accuracy depends on proper vapor pressure calculations and convergence tolerance. Professional psychrometric calculations may use more sophisticated methods.

Q5: What applications use wet bulb temperature?
A: HVAC design, weather forecasting, industrial drying processes, sports medicine, and heat stress monitoring in occupational safety.