Absolute Vapor Pressure Of Water Calculator

Absolute Vapor Pressure Equation:

\[ e_s = 6.112 \times \exp\left(\frac{17.67 \times T}{T + 243.5}\right) \]

Absolute Vapor Pressure (e_s):

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1. What is Absolute Vapor Pressure of Water?

Absolute vapor pressure of water is the pressure exerted by water vapor in equilibrium with its liquid phase at a given temperature. It represents the maximum amount of water vapor the air can hold at that temperature.

2. How Does the Calculator Work?

The calculator uses the vapor pressure equation:

\[ e_s = 6.112 \times \exp\left(\frac{17.67 \times T}{T + 243.5}\right) \]

Where:

\( e_s \) — Saturation vapor pressure (hPa)
\( T \) — Temperature in degrees Celsius (°C)
\( \exp \) — Exponential function (e^x)

Explanation: This empirical equation, known as the Magnus formula, accurately calculates the saturation vapor pressure of water over a wide temperature range.

3. Importance of Vapor Pressure Calculation

Details: Vapor pressure calculations are essential in meteorology, HVAC design, industrial processes, and environmental science for determining humidity levels, predicting evaporation rates, and understanding atmospheric phenomena.

4. Using the Calculator

Tips: Enter the temperature in degrees Celsius. The equation is valid for temperatures between -50°C and 100°C. The result is given in hectopascals (hPa), which is equivalent to millibars.

5. Frequently Asked Questions (FAQ)

Q1: What is the relationship between temperature and vapor pressure?
A: Vapor pressure increases exponentially with temperature. Warmer air can hold significantly more water vapor than colder air.

Q2: How does vapor pressure relate to relative humidity?
A: Relative humidity is the ratio of actual vapor pressure to saturation vapor pressure at the same temperature, expressed as a percentage.

Q3: Why is 6.112 used in the equation?
A: 6.112 hPa is the saturation vapor pressure of water at 0°C, serving as the baseline constant in this formulation of the equation.

Q4: Are there other equations for vapor pressure?
A: Yes, other formulations exist including the Tetens equation, Goff-Gratch equation, and the Buck equation, each with slightly different coefficients and ranges of validity.

Q5: How accurate is this calculation?
A: This formula provides accuracy within about 0.5% for temperatures between -30°C and 50°C, which covers most meteorological applications.