1. What is Vapor Pressure of Water?

Vapor pressure is the pressure exerted by water vapor in thermodynamic equilibrium with its condensed phases at a given temperature. It represents the tendency of water molecules to escape from the liquid phase into the gas phase.

2. How Does the Calculator Work?

The calculator uses the vapor pressure equation:

Where:

• \( VP \) — Vapor pressure (kPa)
• \( T \) — Temperature (°C)
• \( \exp \) — Exponential function

Explanation: This empirical equation accurately calculates the saturation vapor pressure of water over a wide range of temperatures, based on the Magnus formula.

3. Importance of Vapor Pressure Calculation

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

4. Using the Calculator

Tips: Enter temperature in degrees Celsius. The calculator will compute the saturation vapor pressure of water at that temperature in kilopascals.

5. Frequently Asked Questions (FAQ)

Q1: What is the range of validity for this equation?
A: This equation provides accurate results for temperatures between -50°C and 100°C, covering most practical applications.

Q2: How does vapor pressure change with temperature?
A: Vapor pressure increases exponentially with temperature - doubling approximately every 10°C increase in temperature.

Q3: Why is vapor pressure important in weather forecasting?
A: Vapor pressure helps determine humidity levels, dew point, and the likelihood of precipitation, making it crucial for weather prediction.

Q4: How does altitude affect vapor pressure?
A: While the saturation vapor pressure at a given temperature remains constant regardless of altitude, the actual vapor pressure in the atmosphere decreases with altitude due to lower atmospheric pressure.

Q5: What's the difference between vapor pressure and partial pressure?
A: Vapor pressure specifically refers to the pressure exerted by a vapor in equilibrium with its liquid phase, while partial pressure is the pressure that a gas would exert if it alone occupied the entire volume.